The slow decision-making is about three things:
(1) It reaffirms the rank of the VCs. (Status waiting.)
(2) It's a test of the petitioner's social status. (If desperate or low-status, the petitioner will continually seek feedback.) The whole point of the time-wasting deliberation is to weed out the desperate, and more importantly to see if you come from the right social class (and can therefore summon enough resources to make their slow response tolerable) to be funded.
(3) It gives risk-averse VCs, who are driven more by their individual career goals (of being "in on" career-making deals that occur once every few years and require social access) than portfolio optimization, plenty of time to collude, trade favors, and peddle influence.
It will never change or go away. Nor do I think we will see an end to this insane bipolarism in which a company is either overfunded or forced to operate on a shoestring.
VC is just unhealthy for software; it works (because it's the only option) for biotechnology startups that require $50m+ just to get started, but for software it's just kingmaking (work with us, or we fund your competition) that doesn't really add anything.