The 50/1.8 is probably even worse... it can be snapped in half like a pencil (well, almost, I exaggerate a little). It also has slower, noisier, less accurate autofocus, and the image quality is not quite as good. It's a bargain though, for the money.
Yes, the 50/1.4 focus mechanism might be a bit fragile... It's not a "true" ring type mechanism, sort of a hybrid and an old design now.
However I've had my 50/1.4 for 8 years... no problem. It was already well used when I bought it and I have no idea how old it really is... might be 10, 15 or 20 years! I don't coddle it, either.
But I do use it with the hood... always (same as I do all my lenses). It came with the hood, so maybe the previous owner used it too.
There are theories that one reason the 50/1.4 AF fails is if it gets a hard bump on the front of the barrel (which protrudes slightly when focused close).... or, more likely, when it gets a hard bump on the focus ring while stored in a camera bag. The lens hood protects nicely both when set up for shooting and when reversed on the lens for storage. So I recommend if buying the 50/1.4, be sure to get the matching lens hood, too.
Another thing, even though it's called a USM lens and is supposed to be FTM (full time manual focus override capable)... some think overriding focus will cause more rapid wear of the mechanism of this particular lens. I don't know... I seldom manually focus mine.
Lensrentals.com buys a whole lot of lenses and compiles reports on their failure and repair experiences. They noted 20% of a batch of 50/1.4 they bought had AF failures in the first year. But, it's important to note that these lenses probably spend more time bouncing around in the back of UPS or Fedex trucks, than they do taking photos. Also, renters usually aren't very careful with gear and we have no way of knowing if lens hoods were used on them.
So I can only tell you my own experience, using the lens for a lot of years and using all the precautions mentioned above (pure luck there, not because someone told me to do so)... I've had no problems with my lens.
Note that Canon has a one year warranty. If it breaks, they'll fix or replace it.
The closest alternative is the Sigma 50/1.4.... sharp and good image quality.... may be more durable. Hard to say because the Sigma 50/1.4 has only been available for a few years, while the Canon has been around a couple decades. On Fred Miranda there are 336 user reviews of the Canon, compared to 98 for the Sigma. Problem with the Sigma is they very often need to be sent in for focus calibration, cost more than the Canon, and by comparison are large and heavy.