if so, then why this feature is not enabled by default?
because we did take that part unchanged from our bitcoin anchestor
same as all coins who build up on bitcoin code base
but if demand is bog enought we can think about it
that we added the changeaddress= option for diamond.conf seems to me a acceptable solution
because how we know automated what addres people wana use as change address
the risc that no changeaddress setting make wallet heave only exist after a lot years for a normal useage
in that timeframe we can expect code changes that will take care about long term optimization of wallets
so short answer:
yes all kind of stuff to wallet dust optimisations this is on todo list but at low priority because for 99% of users feelable effects are multiple years away