Masternodes were brilliant for Dash. Made thousands of millionaires in the space of two years. There may be downsides down the road that we're not aware of yet. It's worked for other players, but not to the same extent as it did for Dash as far as I know.
Yes and its the trend and there are other coins right now that is adopting masternodes. Also, it a good idea because it limits the coins in circulation, that is pushing the price to go up. I think dash popularizes it.