Railroading is perfectly legal, just hide the tracks!
I use a sand box that goes on either side of the rail road and the tracks will tend to crawl to the path of the PC's anyhow.
BUT, I've been proud of designing an adventure that went much like this: large open area, filled with little adventures, ruined tower here, lost dwarven mine there, small nature refuge with ents, few scattered villages of war like locals... and then had a theme running of an evil schemer that wanted to exploit everyone in that area. The PC's stumbled on his machinations here and there and finally put the puzzle together, pointing at his lair, where they confronted the bad guy.
Beauty was that the locals weren't suffering from his involvement, so they did it all on their own... no major renown, no big rewards, etc.
Railroading does tend to carry such rewards.