[jwr]

PoE is not obvious to implement (take it from someone who has done it with a fair share of mistakes), uses more expensive components that normal ethernet, takes up more space on the board, makes passing emissions certification more complex, and is more prone to mistakes that ruin boards in the future, causing support/warranty issues. In other words, a bag of worms: not impossible to handle, but something you would rather avoid if possible.

[ldng]

And what would a better alternative look like ?

[timschmidt]

I wouldn't call it "better", but the least-effort path among hobbyists and low end gear is often 12v or 24v sent over a pair with Gnd and a forgiving voltage regulator on the other end.

[jwr]

There is none, I never said PoE is "bad": it's a very good solution, it's just difficult to implement.