Free alcohol changes the social dynamic of an occasion. There's less awkwardness about offering to get someone a drink or vice versa. Less concerns about expectations of reciprocity.
And people generally seem to end up drinking more.
Maybe it's different in the US, but as a Finn I don't think "end up drinking more" is good since people generally end up drinking quite enough without any financial help.
And people generally seem to end up drinking more.
All good in my opinion.