Are there any cons? I don’t think there are any over using Requires beyond the time and effort to do the conversion (but, yes, I suppose the situation may be different if you’re converting a direct dependency to a weak one). Here’s a previous thread with a run-down on you you convert Requires to an Extension in a backwards compatible manner:
And as for that list, here are Requires’ dependencies (although this will also catch those that only use Requires for backwards compatibility):
Direct Dependents (566)