You must be talking from the perspective of a JK, not a TJ/LJ/YJ/CJ. The 4.0 inline six is a lot of things, but it certainly is NOT the "weak link" in a Jeep. The mini-van 3.8 V6 put in the 2007-2011 JKs certainly was the weak link in that series.
Im guessing the 3.6 minivan engine is the weak link in the new ones too.....