Well, that's not quite true.
You're viewing weapons as nothing more than a tool.
Like someone picking a car by no other criteria than if it's economical and if it seats enough people.
I'm viewing weapons by their looks.
And that plasma sniper rifle still looks an awful lot like the regular plasma rifle, or even the plasma pistol (although, in that particular case, it's quite different, but look at the pipe weapons and you'll know what I'm talking about).
They're not distinctly different weapons. They're still the same weapon.
It's kind of like the good old Mauser Broomhandle pistol. There was an automatic version, a long barreled carbine, a detachable stock for some of the pistol models as well.
But it's still a "mauser broomhandle".
Nobody's gonna argue with you if you call either of those weapons a mauser broomhandle, because it's basically the same gun in different configurations.
However, nobody's gonna agree with you if you call the MP-40 a Mauser broomhandle.
Because it's a different gun completely.
So while there's more weapon configurations if you count the modding system, there's still fewer base weapons (and thus, visually, different weapon types) than there was in any of the previous games (not counting the original fallout, which only had 21 different base firearms, not counting uniques or named variants with the same look, but fallout 2 had 43 distinctly different firearms, for example).
This is what's being pointed out in this thread.
The amount of visually different base weapons is lower than in the other games.
So we don't get 5 different submachinegun models, for example.
We get 1 distinct submachinegun and 4 automatic versions of pistols instead. (just a numbers example, not a real count of them)
See what I'm getting at?
The lack of base weapons gives a sense of lack of variety in the game.
You don't go around thinking "oh, a completely new weapon that I've never seen before" just because you happen to find a pipe rifle with a marksman stock instead of a regular stock.
You just go "oh, a pipe rifle with a different stock"... the important part here being you going "oh a pipe rifle", instead of "oh, a new model".