The reason i left it separate was to allow the developer to clearly see what is/isn't required for each type of push. When i was learning push i was VERY confused as to what i actually needed to provide when configuring. For BES all you really need is an AppId, unless you are working with the Push SDK and have an initiator URL and credentials. I just don't want to give them a configuration page with a bunch of empty properties and hope they know what to fill in for each.

I do however agree that we should try and make this as easy for the user as possible. No building, Easy setup.
In order to do that we need to distinguish what fields are required for each type of push and when each optional parameter is needed.