What would make you queue? (long post)

[Zojha]

I'd que every day if only my highest rating earned during any point of the season was considered for the final rewards. Then I'd have nothing to lose by queing more with much to gain like better rating.

This is pretty much the solution if you do not want to change anything else.

Rating decay is inefficient because the incentive to play as little as the system allows remains intact and you'd have to make completely ridiculous minimum play demands that would put proper e-sports to shame for it to make a noteworthy dent in activity. And depending your potential rating loss over those game it might well be the better option to just let it decay than take the gamble.

For ranked Feast, the stagnation is simply caused by the reward structure. That's easy to fix. For PvP as a whole, it's a lot more complicated, but I'll spare you the rambling about that - I've said everything that can be said about that by now.