Making the voting power/staking also dependent on the lock-up time leads to a high incentive to lock up your tokens as long as possible. More voting power requires, therefore, living with your decisions for longer. Furthermore, it makes the voting power less dependent on the token distribution by adding an additional variable. It’s a little bit like vesting for everyone
Staking is already a necessary concept in Cosmos, without it the network wouldn’t run. Tokens are already locked for staking in Cosmos, if voting included locking do staked tokens count? is there a double lock one for staking and another for voting? do only unstaked tokens with time locks count for voting?
Just because locking might be applied to liquid tokens in DAOs for voting boosting or weighing it doesn’t mean that can be applied to any system, specially if the system already has locking ingrained in its system.
Systems like Moloch DAO , last time I checked, had liquid tokens that could in principle be locked but there is no necessary staking involved as is the case for Cosmos. There exists, however, a concept of paying a tribute (that could or could not be taken), the same applies to most current DAOs. Locking tokens for weighted voting has to be implemented meaningfully in order to get the most out of it.
If applied to Cosmos it would seem to me an increase in complexity just for the sake of trying new and exciting ideas. I am of the opinion of letting platforms like Edgeware experiment with these concepts given that they also have staking. An alternative is to design a meaningful architecture for weighted voting first and then discuss the possible implications of implementing it.
Voting power is based on lock-up time like you say but voters are also rewarded at market rates for the locking. AND the locked tokens can actually be traded and profited from depending on the proposal outcome.