So much levelling progress is lost if it's resetted to lv.1 and having your retainer to be your desired class is very important because you can gear that retainer with leftover gear very easily.

I understand there is a difference between switching your retainer between gathering (DoL) classes. If you have a lv.50 botanist and miner, if you were able to freely switch your retainer bewteen the two classes and still be lv.50 then you have much more flexibility in what you want your retainer to gather. SE would honestly encourage us to buy another retainer instead for more money instead.

But again for DoW there is no difference in what each class can potentially gather. They all can gather exactly the same items. So this flexibility option isn't as valuable and the level reset honestly feels too much.