Looking at the first example it seems that this might discourage someone from voting for the return (large) proposal if they want to retain the full voting weight for the other smaller proposals. This may have an unintended effect of lower threshold of return (or burn, if exists) proposals.

Having the ability to vote against specific proposals may mitigate this which would allow preventing a particular proposal from being funded without affecting other proposals that a voter might abstain or vote for, even in a high participation scenario. The return proposal is expiring in 4.5 years and would be costly to recreate under the current fee structure so the best time to implement it would be before that expires.