Hmm ... long post lost to preview button .. fk it, here's the summary:

1) Fix respawn timers: This should not even be debated imo. If CCP is worried about the effect on the economy, see pt 2

2) Invert pay-out penalty: It doesn't make sense to me that Concord pays less while sites are harder.. Inverting the pay-out penalty will encourage fleets not to skip hard sites under influence, and will reward the people who put in the most effort instead of the leeches who just wait for easy-isk. For me this addresses the main issue which imo is a mind-set one - people think it's ok to ruin everyone elses fun because incursions for them = risk-free isk rather than hard-fought battles. This also limits the time that people can get max payout, which in turn limits the effect of insta-spawning incursions on the economy.

3) Fix red-bar degredation: Make it slower ... this could even be a fixed 2-day timer or something. What you want is for people to have to make a decision when a new incursion spawns: Stay for less payout, or move for more? If everyone moves, you run the risk of losing the LP, but you also can't force the mom to spawn too fast. For me this has 2 key benefits:
a) New communities form which specialise in closing out < 50% influence incursions, and have lower barriers to entry (newbie friendly). Older communities move when they choose to move, and earn higher isk but at higher risk.
b) Bickering over the mom virtually disappears as the fleets who generally are involved in said bickering have already moved on to the next site.

4) Make the mom kill mean something: At the moment, one fleet can grind for hours to get the red bar blue, and then another (potentially weaker) fleet can just warp in and ruin their day by killing the mom. Initially I thought "Just suspend concord inside mom sites - let them fight it out", but given the bickering over losing a contest (30mil isk), I'm not sure what would happen if people started losing their 5 bil Vindi's! Free PVP would probably also draw griefers to incursions like a fly to ... jam? So instead, how about a gate-key that drops from 1 random site while influence >50% but is tradable? The fleet that finds the key gets to decide who closes out the incursion. If/when they leave to a new high influence incursion they can sell / donate the key to one of the "Newbie incursion" communities. Alternatively, entrance to the site could be based on more realtime data - e.g. only the fleet with the highest avg damage+healing in the past 6 hrs is allowed in.

I know I am new to incursions (and EVE in general), but that is my 2p