The phrase "endear sb to sth" means sth causes someone to draw affection for it.
e.g. The puppy's playfulness endeared it to children
Translate:Children feel affection for the dog who is playful.
Even the boot is inanimate,in such a structure,is passive.It's features are the active force.

我觉得楼主的看法是对的。原句不是非常严谨，按照endear的一般用法，应该是the features endear the boots to customers，因为endear是“使…被喜爱“，它的直接作用对象应该是【被喜爱】的，也就是说“使靴子被顾客喜爱”，而不是“使顾客被靴子喜爱”。
我觉得原句可能是一个遣词造句比较随意的母语人写出来的。