All you're really saying is that Smith plays best when someone better covers up his mistakes, which is true of every bad defenseman. Smith isn't even adequate defensively on the second pair. Put him on the first and you destroy that pairing (since Kronwall isn't a shutdown guy either). Good first lines would MURDER that top pair. Also, Smith has been paired with Dekeyser and Lashoff (both responsible) plenty this year and that hasn't noticeably improved his performance...so you can't blame it all on Quincey and Kindl. You can't move a guy up to the first pair simply because he's a disaster with every other guy on your team.
The only solution I see is to get a second pair defenseman at the deadline, drop Smith permanently to the third pair with Lashoff, and trade/waive Kindl or Quinecy. Either that or accept that your defense falls off significantly after the first pair.
Kronwall and Smith didn't get murdered playing together at all. They did it the entire time E was gone and were fine at both ends. That's why I suggested the pairing -- Quincey and Kindl don't make Smith better, but Kronwall did.
Also, I hardly recall Smith playing with DeKeyser at all. Maybe Lashoff some, but Smith's partner was almost exclusively Quincey before E was hurt.
I do agree that getting another d-man is imperative regardless. Someone that can move the puck and chip in offensively is a big need for the Red Wings.