A paltry sum in the larger transportation picture, for a system that has generated significant positive economic returns in the form of property and business development in other cities, and should get the benefit of the doubt at this point. But apparently that isn't good enough, and nothing will ever be good enough, for some skeptics. I just wish I could understand the skepticism better, because the evidence is so strong and so one-sided at this point that I can't even believe it's about evidence anymore. It has to be about some bigger cultural or symbolic concern. No one primarily concerned about economic development could vote against it at this point.
I think the resistance is that people expect a large transportation investment to provide mobility benefits. The truth is that streetcars won't take you anywhere any faster than a bus could if everything else were equal (see Human Transit for more details).
However, streetcars do improve the quality of the transit experience (e.g., smoother ride, more spacious vehicles), and evidence shows (as you noted) that they encourage development along the line. More development means you can reach more destinations in the same time, so there are accessibility benefits even though there are not mobility benefits.
I think streetcars should be thought of mostly as an economic development tool with some transportation benefits. For that reason, I think the funding source is important. I wouldn't want to see the streetcar divert too much in transportation funding from other projects. I'd be okay with maybe 20% of the cost coming from normal transportation revenue sources, but I guess that's just a personal opinion.