First of all, the competitiveness of a team highly varies from split to split. There have been plenty of teams that perform well for a split or two, then end up at the bottom of the standings next season. Therefore, the recent performances of a team weigh very little when considering them for a permanent LCS spot.
What's to say that one of the new NALCS teams won't buy all/most of the IMT rooster, practically keeping it intact and only changing the staff around it. The players will not be gone, they will likely just move to different teams. You make assumptions on the competitiveness of the region based on 0 information, as there is no information about the new teams yet.
Also Misfits moving to the NALCS would have done little for the competitiveness, because of the import limit on teams. They would have to play with practically an entirely new rooster. Who's to say this rooster would be as competitive as the current Misfits?
I'm glad non of the EU teams got accepted into the NALCS. NA should concern themselves with growing talent within their region, instead of just importing everything from better regions.