I have also noticed an user-unfriendly feature which is that some of the previously running wallets seem not to run any more and suddenly I can't reinstall a wallet due to a "lack of  space" issue.

There's a limit on the number of applications that can be installed because the available flash is relatively low and there's a significant amount of duplicated code. We plan to address this in the future (by optimizing things around and grouping applications together), but in the meantime you can just delete the coin applications you don't need right now and reinstall them when you need to transact. Nothing is lost as the private keys never leave the device.