You can say "trop de temps" but it may change a bit the meaning. "Beaucoup trop" is a way to say that it was "far too/way too...". In French, I would explain the difference like this : -Vous avez mis trop de temps : but it's ok just this once. -Vous avez mis beaucoup trop de temps : and this is not ok at all.

vous n'avez pas mis beaucoup de temps You haven't spent a lot of time... You haven't taken a lot of time... vous mettez beaucoup trop de temps pour y allez You spend too much time going there./you spend too much time to go there.

* pour y alleR ;-)