Mountain bike components require replacing faster than a road bike? Where ever did you get that silly notion? As long as you maintain the bike and don't leave it out in the elements...

The low end components hung on a decent frame is an old product manager trick to keep the complete bike price attractive. I would personally stay away from anything 7spd or even 8spd. Nothing wrong with them, they'll work but the parts will be low end and on the heavy end. The standard these days is at least 9spd.

I can't speak to the Suntour fork. That's another cost savings measure decision by the product manager. 80mm is the minimum for a 29er, woould be a bit on the short side if it were a current model 26er.