I think the reasons so many europeans (including me) think baseball is boring is the same why so many americans think football is boring. They (We) just don't have a clue about the game
of course, I'd never admit this in a regular my sports is better than your sports pissing contest
Most things in this world are "boring" to those who choose not to understand them.
And we are all naturally biased towards what we grew up in/with.
Complaining that "nothing ever seems to happen in this sport" is merely a sign of not knowing what to look for, much like the stereotypical American who watches a series of back and forth passes over the midfield line in a soccer match with no apparent consistent attempt to move the ball towards the goal, and bemoan that nothing's happening, its just a bunch of guys kicking around, and why doesn't this boring game have more scoring in it?
Too true, too true.
Another couple of points on baseball:
It may not make great television, but baseball is hands down the best
radio spectator sport out there (barring perhaps cricket, which I've never heard). Football (whatever variety you prefer), hockey, basketball all lose something when you can't follow the action visually. Baseball, on the other hand, is almost better when it's just Vin Scully or Harry Caray's voice coming across the ether. All the down time during the game, which may be a negative live or on TV, provides a quality storyteller, like all the best baseball announcers, the chance to connect baseball's present with its past, its traditions. Also, baseball's static nature allows the listener to more clearly visualize the action described: "Fastball, high and tight" or "A harder chopper over the mound" provides a more precise image than "Giggs. Now Rooney. Back to Giggs". And finally, the clear, clean crack of bat on well-struck ball is maybe the only sound in sport that needs no clarification by announcer or reaction from crowd to let you know someone just scored.
Baseball is also much more cerebral than most other sports, which are much more visceral. The mental battle between pitcher/catcher and batter trying to out think each other on pitch selection is a subtlety even most actual baseball fans don't follow. And being a game of percentages, it's a numbers geek's wet dream.
Finally, the length of a baseball season is unique among major sports. American football teams play sixteen times a season. Rugby teams play what, around twenty-four a year plus maybe half a dozen cup ties? A domestic footy season is thirty-eight, forty odd games, with top teams adding maybe a dozen cup ties. Even basketball and ice hockey call it quits after eighty-two. Every baseball season runs, some would say drags on, for 162 games, five or six a week. This demands a measure of consistency that sports with shorter seasons don't, though said sports are usually much more physically taxing. All this means that following baseball is often more about following the season (more joy for numbers geeks) than the game. Also, when professional sports came of age, the man in the stands (who probably worked ten-plus hours a day in the factory with a half day on Saturday) would have had a hard time accepting an athlete who only had to perform once a week as an honest working man.
Overall, baseball, like any sport, is an acquired taste. It's also very much a product of the 19th Century, seeing its true heyday from the 1920s to 1950s, during, not coincidentally, radio's greatest era. As such, it may no longer have the cache it once did the US, and, as an American creation, it never caught on in Europe (parts of the Far East and Latin America, lacking indigenous club sports or pro leagues, snapped it right up). The other major sports may have roots in the 19th Century, but all have become much more prominent more recently, and this is arguably due to television bringing their fans excitement that radio was ill-equipped to convey.