Suh is good and all, but the front office has proven they can find guys to play DL at an acceptable level. The defense doesn't need much.
The offense on the other hand needs a lot. The line is bad. If Lynch wasn't a beast, and if Russel wasn't an escape artist, they'd be exposed for the shit that they are. Upgrading WR sounds nice, but I'd much rather have an improved O-line so that they can still run the ball effectively if/when Lynch leaves/retires. Or protect the QB they are about to invest a lot of the cap into.
Suh is an extravagance we (I like to say "we" so it sounds like I am on the team) simply can't afford.
Only problem with that logic is that
Wilson IS an escape artist and in limited carries Turbin averages 4.0 ypc over his career and Michael averages 4.9 ypc. Not saying either are Lynch (so don't twist), but they'll find a reasonable RB or two to fit in whenever Lynch retires.
They do need help on the OL ... and I'd expect that they'll find 2 pieces in the offseason.
To say that Suh wouldn't be a massive upgrade is an understatement. He'd contribute to increasing the ability to put pressure up the middle on the QB, limiting their ability to step up in the pocket, and making the outside rushers more effective. Moreover, the one way right now to beat the Hawks is the short passing game which requires the DBs and LBs to not have 100% confidence in the DL's ability to get to the QB by a certain clock such that they have to give up some room on those underneath routes. If you limit the amount of time that the QB has to get rid of the ball, those underneath routes become far more difficult to complete and get YAC on.