Thanks, not really doing me much help linking to translation sites, if I am to be honest.

To start off though, you are entirely right about に, I jumped the gun on that one.

The native correction is indeed a better wording of your original Japanese sentence.

外にいる人に部屋の中が見られやすいホテルとして有名です

"It is famous for a hotel where the rooms can easily be seen into by the people outside."

This makes it seem like out of all of the hotels where the rooms can be seen into by passersby, this one happens to be famous. This is also why として does not fit your English meaning. "A hotel famous for" is quite different from "famous for a hotel..."

外にいる人に部屋の中が見られやすいので有名なホテルです。

This one fits better. "It is a famous hotel because the rooms can be easily looked into by the people who are outside." Again though, 外にいる人 demarcates a subject and doing so in Japanese, so you are therefore selecting a specific group. This sounds awkward, because it does not sound very unspecific like "people outside" does in English. Instead, it is literally "the people who are outside."

Secondly, 見られる and 見える. Are you saying that it's easy for people to willfully look (like peeping) into the rooms, or are you saying that the rooms are readily visible (like easily seen)? If you're going the peeping route, stick with 見られる, if you're going for wide windows type of stuff, go with 見える.

外にいる人に部屋が見られやすいホテルとして、特に人に見られるのが好きな人たちから大いに支持を受けている有名なホテルです。

"It is a famous hotel for being a hotel where the people who are outside can easily see into the rooms, especially receiving large support from people who enjoy being watched."

Lastly, for the やすい + 有名 comment, 有名 is a な-adjective, making it a noun, firstly. It is definitely an awkward shitshow to put them together that way, but grammatically it works.

Maybe I'm just misunderstanding, since you never providing any context.

Is this a hotel that's famous for the rooms being easily seen like large windowed cafes?

Or is this a hotel where you can be an exhibitionist?

Because I translated assuming for the first scenario. If I'm mistaken and it's the second case, definitely go with the native correction.