That's a great idea, but I would argue it should be higher for primaries, with 4 weapon types (special only has 3 and heavy just 2) being the biggest reason. 4 exotic autos, 3 exotic hand cannons, 2 exotic pulse rifles, 1 exotic scout, and then 1 each of sniper, shot gun, and fusion rifle. That's 13 right there, with another eight raid primaries, and 3 iron banner primaries. Throw in another 8 from both crucible and vanguard vendors, and another 4 for the three factions, that's a possible 50+ primaries, not including the pre DLC vanguard and crucible primaries.