The American Marshal plan realised that a weak Germany would mean a stronger Russia, which was a far greater risk.
First of all, it's not "The American Marshal Plan".
It's just, The Marshall Plan (officially the European Recovery Program, ERP). And it didn't just assist Europeans, it provided benefits to Asia as well. America didn't help Europe to counter Russia. In fact, America offered money to the USSR, but they refused, and also disallowed Eastern Euro countries from receiving anything.
The reason was we saw how helpless Europe was at taking care of itself, and they needed a lot of help economically on many levels, not just financial injections. American agencies did studies on how to rebuild industries in Europe and improve European productivity. Europe needed heavy assistance from America since the Lend Lease program. To get things back to normal, and the fact that Americans sympathized with the poor, incapable Europeans, economic assistance was provided.
We didn't need Europeans to be economically well off to counter the USSR; that was never the objective. If it was, we would have saved the money and turned it into a giant forward operating base. We could easily have annexed Europe; sympathy is the reason we let Europe have it's own sovereignty.