Having the At-large elections in the midterms is actually beneficial on its own merits, even leaving aside the concern about lengthing the terms, cutting the number of elections there by half.
Right now, you have essentially an election every two months that is federal of some note in nature and gets people back focused again. However, with this proposal you would lose that aspect and have to hobble across a four month span with no such election.
Remember even pre-reset, the At-large Elections were always in the midterms going back to their inception, while Regional ones were in the Presidential years.
What if we switched the At-Large elections to the midterms and scheduled the regional/subregional elections to go with the presidential?
I agree with NCY that this amendment would have the effect of decreasing activity, which was not the intended goal of the new Constitution. I would be open to supporting the at-large elections for the midterms.