—the railroads purchased the state legislators, who then sent the railroad candidate to the senate-—
They hadn't built roads at the time so there really wasn't any alternative to them.
If you didn't pick the railroad guy to go to the Senate you would have ended up with another guy, different name, who had remarkably similar views.
Increasing the size of the electorate (from the legislators to the public at large) didn't do a whole lot ~ in many states it simply handed over the selection of the senators from the legislature to the Ku Klux Klan!
“the railroads purchased the state legislators, who then sent the railroad candidate to the senate-”
Is that significantly different from what we have today? The special interests give lots of money to certain candidates, regardless of whether they are in their state or not. Even Scott Brown got money from conservatives in other states.