Re: Add-ons become obsolete with the phone... and if they're not very cheap....
It would be enough it they were supported and compatible within the same brand - outside true industry standards you rarely see add-ons interoperability across brands.
Just these are mostly gadgets in attempt to get maybe some more sales, and make some more money selling yhem, while add-ons support in different models will put some design constraints I guess they don't really want.