All automatics are bad if not properly maintained and cared for. Mechanically the 5R55E is the same transmission as the 4R55E that was used in the Rangers since the mid 90s, a stronger variant of the 4/5R44E used with the smaller engines, and an evolution of the A4LD. The 5R55E is arguably the strongest and most reliable of the 1983-2011 ranger automatic transmissions.
Keep in mind people are more likely to post complaining about the bad than the good. They certainly aren't going to say that it failed because they went 150k miles and towed heavy without looking at the fluid.
Even a manual transmission has wear and tear with miles. Generally that manifests with worn out clutches, slave cylinders, and maybe shift fork bushings. Except for the latter those things are external to the transmission. An automatic just moves those wear points internal with bands, frictions discs, etc. Since it is internal all of the residue from that wear mixes with the fluid, then get deposited and causes wear in other parts of the transmission. Keep the fluid level and condition good, keep the temps down, don't tow overloaded (and in overdrive) and the things can last a long time. If you're going to be towing regularly, maybe install a trans temp gauge to monitor temperatures, and an aux transmission fluid cooler (or bigger one) to keep them lower.
Of course since it's the wife asking, all automatic suck and are terrible. You MUST have a manual if you want any reliability and longevity.