Don't get me wrong, I agree with you on individuality, it's the identity they lacked. A lot of the individuality was directly related to the builders experience in road frame building where indiviuality was rife (things like the GT triple triangle, the e-stay, sloping toptubes, multi-tube designs, the use of alloy or Ti all came from road builders). I just feel that the identify of an MTB (fat tyres, solid frame and decent sizes to suit short arses) wasn't there until the cookie cutter phase, but as you say, it came at the expense of the individuality.
I remember my first 'mountain bike' in the early eighties, a Vindec Trekker. It was a real original with 2" fat 29" (ish) tyres, a bent TT, risers and truss forks (imagine a Jones DD frameset or a Black sheep but 25 years ago!), very individual, but not a classic MTB. Much the same with my late 80s Cinelli, loads of stunning details on the frame as you'd expect from a top Italian builder (this was a euro Cinelli, not a GFisher US one), but if you put thin tyres and drop bars on it it wouldn't have looked out of place on a cyclo-cross course.