I think there are a few reasons not to do this:
- Not as easy to incrementally load dips, once you get strong enough. Practically speaking, how much weight are you going to want to deal with hanging between your legs?
- Anecdotally, people seem to have more issues with injuries from dips than bench.
- Bench will improve to a point from dips for a novice, but not much in the long run.
- Most people will be able to move more weight on the bench. If you care about strength, and strength is the production of force against an external resistance, then bench is probably better.
- You say you like bodyweight exercises. But, the dips will not be a bodyweight exercise for long...? Not sure what to make of this.
Basically, I don't see any good reason to make this substitution. But if you like dips more than bench, and want to do them, don't let me or anyone else stop you.