Note that if you combine all of your UTXOs to one address using a single transaction, any blockchain analysis software will know that a single person owns all of the addresses.
It is probably better to leave them like that if the inputs are large enough, i.e. no 10000 sat outputs lying around, and to combine only the dust inputs (even better, send the consolidation transaction through through a mixer first)
Yes, but still when an average user will send any amount of bitcoin to someone, electrum by default will create two outputs, one to send the amount that you send to the other address and the other output to send the entire balance of the wallet to the change address. So this will automatically combine all of your UTXOs to the change address.
Not everyone about coin control feature and not everyone is techy (or even willing to) to do all these complications.