Bringing prizepools to divisions below invite has the potential to be a positive change to the format, while also having the possibility of being damaging. (If mishandled)
Getting enough teams for ADV this season was a struggle to say the least. But when you stop to think about it- what incentive do people really have? Why should joeblow2005 challenge himself against the upper echelon of players in advanced, when he can attempt to roll main for the 3rd time in a row?
Bringing prizepools to advanced would be a great thing to try- it would incentive people to try and move up, while also keeping more players in circulation. (Less potential RR, and less reason to sandbag in lower divisions) Definitely worth a try.
In terms of the other divs, (main/intermediate) in my opinion, should not be touched. If the prizepool is extended to ADV and nothing further, it will certainly keep it feeling more special, and sought-after. (As it should be) Intermediate prizepools would not be smart. many players there are new, and the increased competition would likely drive away more than it would bring. As for main, I personally disagree as well for a similar reason, but at the very least a poll or something similar should be done. (Something that includes main players in the decision)
TLDR; Prizepools in advanced are a no-brainer, intermediate would be unwise, and main should be carefully considered.