If you only count "Pipe", "Laser", "Plasma", &c. as one weapon in FO4 but count the Laser Pistol/Rifle/Trilaser &c. in prior games as different weapons you're a hypocrite.
But in Fallout 3 and NV all three of those weapons are significantly different, appear at different parts of the game, and are paced differently.
significantly different
Whereas in Fallout 4 when you have a laser pistol/rifle/autorifle/sniper rifle the only differences are their damage, recoil, accuracy, rate of fire, type of sights, degree of zoom, effective range, movement speed, and physical appearance.
appear at different parts of the game
Blatantly untrue, unless you're trying to split hairs about the laser pistol that you get given before you even finish character creation in NV. All the different sorts of low-tier ballistics, high-tier ballistics, lasers, plasma, and exotic weapons appeared in waves in prior games as well.
paced differently
I have no idea what you're talking about here, unless you're repeating the prior thing or complaining about the rate at which they appear, in which case I'd have to reiterate the fact that New Vegas gives you a laser pistol before you finish character creation and lets you buy a plasma pistol from the shop in the tutorial level.