I wouldn't mind, I'm just making the point (regarding the OP) that if you want people to take Sentai "seriously," dubbing's really not going to be a better alternative to Power Rangers, at least as far as the US is concerned.
The US is going to be xenophobic, no matter what. Even
Doctor Who isn't as super-mainstream as we hope it would be, despite airing on BBC America. (You can't even find
DW toys at Wal-Mart or Target, which would be great.) Anything that's foreign AND popular, Americanize it. That's been the US value since 1993. And we've seen the unfortunate Hollywood-ization of Japanese properties (especially anime). Americans are afraid that their patriotism isn't adequate, and lots of Americans are getting into foreign stuff, and thus, all those big Hollywood stars will be shunned away. They don't like that. So they jump in on those foreign properties, and Americanize them. Dumb them down.
But then, dubbed or subbed, these shows were never meant to be taken super-seriously. Kids will get into it, adults will laugh at it, that's the way it's been for me as I grew up. It doesn't even bother me anymore. If anything, I'd rather hear "cheesy and campy" than "GO GO POWER RANGERS!"