Are you saying that historically Indians where not forced onto reservations, or that now there are no pressures to keep them there?

The other operative word is "is". No one is trying to defend the history of the united states... slavery was a rather common thing at one point.

There is no threat of punishment keeping them there. They are free to live their lives anywhere in the US the same as any other US citizen. They do, unfortunately, have a higher percentage of poor people than most demographics, but being poor is quite obviously better than being kidnapped and tortured.