Also, the purple monopoly sucks.
I only mentioned the Purples/Browns as an example that the cheapest hotel still has a higher rent than having all four railroads. They're still terrible, but I was just illustrating that railroads will never get you more than $200 on a hit, while any single hotel will snag you more, even the pathetic Purples/Browns. Also, I misspoke. I omitted some details, which could lead a reader to assume that you can build up all the Purples/Browns $310. While it does cost $310 to build up Mediterranean, you need to build up Baltic, as well. Both of these would cost $760 to fully develop. Sorry about the confusion.
And you're right that those other properties cost more to develop fully than the railroads, but the rewards are far greater. For example, the light blues cost $1070 to fully build. A single hit gets you $550 or $600. Two hits will pay for the investment. For the railroads, you need four hits just to break even (unless you buy the railroads for cheap, which is certainly viable). The oranges start to pay off after 3 hits. What's more important than the number of hits to recoup your losses is how much more those hits will earn you. After that third time of an orange getting hit, each subsequent hit gives you about a grand. Each railroad hit? Still only $200.
Railroads aren't terrible, but they're slow. When money bounces back and forth between hotels, it'll be your own hotels' rent that protect you from someone else's rent. Railroads won't be able to keep up, not evenóI suspectówith the uniform distribution and more spots.
Although, I'll gladly buy one or two to use in bartering. If I can entice someone into giving me a color monopoly, I'll gladly give him a railroad monopoly and see if I can't squeeze a little something extra out of him. I won't badmouth the railroads during an actual game.