There are definitely both trade offs in UX and engineering challenges in implementing, but the option should always be there for users.
The alternative, the outcome many users find themselves with right now, is horrendous.
Discussion
The option was always there for the users: run own dojo, which they always repeatedly and most users did.
Sending xpubs to dojo was not a whirlpool requirement (sparrow iust uses electrum servers). It was purely a UX decision to make the experience on mobile bearable.
They justified in an interview that for the postmix account (which can have hundreds of transactions), using block filters requires gigabytes of network traffic. For mobile that is simply unacceptable.
So mobile data usage is unacceptable, but potentially having your customers full wallet info in the hands of federal agencies is acceptable.
Got it.
They are both unacceptable, that's why most people used their dojo. If it were up to me, no wallet would have a default node, regardless of wether it's a dojo, electrum or bitcoin-rpc