Why do people like streetcars so much?

Will, a loyal MR reader, asks:

I just ran across an interesting post by a Jess Weiss on a
pro-streetcars-for-DC blog that asks the following question – "In
several places in the U.S., most notably Portland, Oregon that's built
the most extensive streetcar system in the U.S. to date, they report
"people simply like streetcars more than buses", but nobody seems to be
able to really point their finger at hard data why that is.

Why do you think streetcars are better than buses?"

Here in Lisbon the streetcars are full of pick-pockets, overcrowded, and hard to keep your balance in.  Yet those same streetcars are beloved by the tourists and common on the postage stamps.

I believe this is a question for Mrs. Cowen, not me.  I did ride them in Lisbon — once.  I'm still wondering why so many people are reluctant to take cabs for cheap, short rides.

Here is a Megan McArdle post on streetcars.  Natasha believes that street car lovers wish to "affiliate themselves with the past."  (When I heard this phrasing I realized we are no longer newlyweds.)  I believe that streetcars help you avoid that "low class feeling" which all too often comes from riding on the bus.  The whole point of a streetcar is to avoid creating an ambience separate from the urban trappings which surround you.  Which is precisely why they are charming yet not always so comfortable.

Here is a short article on the popularity of streetcars.  Putting aside the social cost-benefit analysis, and focusing only on the individual ridership decision, why do people like streetcars so much?