I mean, yeah, sure, we've all played the game many times, but going to New Reno before you go to NCR is kinda sidetracky AND can easily make a new player sorry for making that sidetrack.
Huh? What?
It obvious that Fo2 route is Klamath - Den - Modoc - VC - Broken Hills/New Reno - NCR and then just east to SF and Navarro, with Redding in the middle.
How is it obvious?
If you get to VC you get the "become a citizen" quest which builds onto the main quest (or looks like it will, entering the vault might and does provide info). You also get "scout gecko" quest which goes nicely along with it. You do gecko, you become a citizen. You also find the location of Vault 15 from the vault computer (I think). Next quest you get from the guard captain who had you scout gecko is to scout NCR. No reason to believe this isn't the way to go.
You MIGHT also get the "bring suitcase to bishop" quest, but it looks nowhere as important. The previous scouting quest led along the same way as the quest which had you become a citizen and got you loot and info.
So you go towards NCR and you may or may not stop at either Raiders or Broken Hills. If you're playing RP you probably won't even find the raiders. If you stop at BH, you MAY get a quest to get the mine parts from New Reno, otherwise there's no indication to go there at all. Especially if you walk into the mine and decide you don't have the right armor yet (which you probably don't).
So you continue to NCR.
In the end it's more about the way NCR is designed than anything else - if it had a different loot/X/shop inventory/random grind drops distribution it'd all work out fine as is.
It shouldn't have it, cause NCR is designed to be in late game, after NR and so on?
I'm completely not getting your vision of NR being after NCR, even the game itself denies it by rewards/quests/and the looks of worldmap.
Yes, NCR is currently designed to be in the late game, except the VC scouting quest and the lack of solid, convincing reasons to ever go to NR has always, in every playthrough where I didn't use out of game logic, had me reach NCR before NR. If you set out south to scout the route to NCR for VC, and not get sidetracked by either the suitcase or the BH mine parts quest, there's no hook for NR at all.
Yeah, it was designed to be reached before NCR, but it wasn't properly connected to either the rest of the world or the geck quest. VC leaves you with the choice of scouting a location for a legit quest giver and delivering a suitcase for a random bum. Doing the obvious thing gets you to the end game, and delivering the briefcase takes you to New Reno and can get your car stolen and you shot. And the car is stolen because if you're just popping in for the only 2 fetch quests in the game that take you there, you'd have to ask around for it and get involved, since whoever made the game knew that you weren't really given enough reasons to be there by the game at all and at best you just got a bit sidetracked from what you set out to do and thats get to NCR. If you don't get sidetracked, you're at NCR before NR 100% sure.
EDIT:
In fact, without previous knowlegde, it's rather easy to screw yourself out of the hooks for NR which are there:
a) If you don't talk to Moore, and he doesn't look important. He looks like NPC's which often don't have anything to say.
b) If you do talk to Moore, but don't take/get the quest from him
b) If you piss Moore off and still take the briefcase, or ask for a reward. This can in fact lead you to one of the few situations where you can't reload after a conversation to get out of getting shot since you screwed up a while ago. So you're less likely to even take the quest on your next playthrough as you can't figure out what went wrong without a guide.
and in broken hills you can either blow the mine up which I don't think requires a trip to NR, or you can decide to do it on your way back. And the fights in BH are so easy, and most quests just dialogue, that making that sidetrack makes you feel like you really ought to be more ahead in terms of zones, you you're more likely to continue towards NCR than make another sidetrack to NR.
Missing the NCR scouting which takes you from VC to NCR requires you to not talk to a guy who looks like a legit quest giver and ASKING him for somethign to do, after you've previously done something for him which turned out great.
Really, the only thing that indicates that NR was supposed to be done before NCR is the XP/loot/shop inventory and guard power composition in NR and NCR, if those were swapped around everything would make a ton more sense.
And this is IMPORTANT:
if you only concern GECK, then you probably ignore Raider.
but if you concern how to change the world, it won't be wasted.
Ah, see, it's a bit deeper than that. Before you find the geck, you have Hakunin appearing all the time reminding you about your quest. There is nothing in the game that indicates that you have plenty of time (in fact after years of playing I still don't know if I have to do the GECK quest on time). The game creates a sense that you have to find the GECK first, and THEN change the world. There's no reason whatsoever to doubt this (without out of game knowledge). If you play it like this, and there really is no reason to even think it wasn't ment to be done like that, you'll get to NCR smoothly and get involved with NR when the deathclaws ask you to get the voice module (which you can get in NR), or if you have the VM from VC, after the geck quest ends.
If finding the GECK wasn't supposed to be endgame/lategame but just the first thing you do while you're on a clock, which makes more sense than anything, then NCR should've been adjusted to come before NR. Then you'd get the equipment for dealing with the Enclave from SAD or the electronic lockpicks for the Toxic Caves - it all works perfectly without any out of game knowlede.