People are confusing performance with practice. Play to a metronome when practicing but you gotta let go of that crutch when actual playing time comes.
The metronome isn't to blame for stiff playing, it doesn't play your guitar for you.
Besides, there are more creative approaches to metronome practice other than "TOK, tik, tik, tik, TOK, tik, tik, tik"
A great example is Tomo Fujita's vid clip on Youtube
He is far from stiff and he's playing Blues, Funk and R&B grooves.