I don't know, a lot of those NME writers of the early 90s were associated with the chortling Wonder Stuff crap, I guess.
There was a dynamic between NME and MM in the early/mid 90s whereby MM would 'break' or cover bands early on (see the 1992 'Best New Band in Britain' Suede cover before they'd even released a record) and the NME would take over the push once success had been established.
Also, MM was much more in the tradition of the old iconoclastic NME epoch, raves and assassinations and writers unafraid to be pretentious (although this was actually only a small cohort of MM writers, in reality). They also undoubtedly covered more new music (or at least Simon did) and would be unafraid to boost traditions outside rock. I still have a copy of a May 1994 edition which had 2-Unlimited on the cover and contained a family tree compiled by Peter Paphides and Simon Price tracing the roots of Eurodance from Hi-NRG, Disco, Philly Soul and Kraftwerk. This was expert trolling of a predominantly indie kid readership and I lapped it all up (and learnt things). Simon Reynolds would stuff his singles reviews full of jungle releases and make E-Z Rollers single of the week when even the music magazines were pretending this music didn't exist. Meanwhile, at NME you had Stuart Maconie, Andrew Collins, Johnny Cigarettes, etc smirking away about Sleeper or something, gearing up to be vox pops on 'I Love the 1970s' or Radio 6 DJs.