Client: our app has low ratings, we fired our previous dev company and hiring you instead.
Us: all right, seems like to make a better app we need 5 months.
C: you're kidding, do it in 6 weeks.
U: Ok, but we'll have to drop some features.
C: get rid of X and Y, nobody uses them.
U: deal!

... 6 weeks later...
U: here's the new app: better graphics, easier to use, more stable and more future-proof.
C: Cool! Let's deploy!

... 2 days later...
C: we just released but the users are really pissed off!
U: what do they say?
C: "what the fuck happened with X and Y? they were the only thing we're using! what a load of crap! 1 star"

Dear client, next time get to know better your users...