Coming from someone who has taken piano lessons for 3+ years and never bothered to learn scales, I can attest that scales have not become obvious to me.
Piano is different than guitar because (from my limited knowledge) guitar songs are mostly based on chords while on the piano the chords are often broken up into individual notes, eliminating the need to memorize/remember specific chords/scales.
A lot of guitar music, especially on the net, is written just as chords, which may be what you're thinking of. But the chords are the same notes whether you're playing them on guitar or piano. You could play exactly the same thing on piano as the guitar players do, and aside from sounding a little stiff, would make good musical sense. It's also common in pop and jazz for piano players to read off chord sheets (lead sheets).
Likewise, guitar music can be written out note-by-note just as piano music generally is. Classical guitar music is written this way, as well as rock leads.
Here's the thing about it, though. If you're thinking of it as individual notes, you're doing it the hard way. Scales and chords are a form of compression between the page and your brain, just as gzip is a form of compression between the web server and your browser. Once you figure them out, you can look at a measure and know what keys you need to hit without having to look at each note individually. Playing any instrument becomes much more fun once you have that skill.
Without first-hand knowledge of the benefit you could get from playing scales, I'm not sure what you're attesting to. You've managed to get along without them. That's fine. It might not make a noticeable difference after a few years of playing, but if you keep going, there are technical holes in your muscle memory which you don't even realize you have, which scales would help fill. (It's this way for everyone, BTW.) I still get benefit from scales after 25 years, and actually enjoy them much of the time-- when they're savored and played in fun patterns. The time to play scales in piano practice can be a lot like the meditation portion of a yoga routine.
On the other hand, if you're just playing "for fun," and aren't hitting any major technical frustration points, then whatever. Keep having fun. Just remember that if you start to not have fun, there are "icky" things like scales which can help you keep advancing. Scales can begin to help at any point in one's musical life.
I mentioned this briefly in the post, but I think this logic, again, puts scales on a pedestal.
I don't want to be a great pianist, I just want to be decent at expressing myself in musical form. For awhile, I thought this meant scales weren't really for me.
It turns out that, on the contrary, they are ideal for me because they quickly get me up to speed on what tends to sound good.
Ultimately, you're right, but scales may be worth a glance even if you're somewhere in the middle!
If you really enjoy getting to the heart of "what sounds good," you would probably enjoy adding more music theory to your study. Make sure not to stop at scales, and move on to intervals, chords, and the circle of fifths. :) Eventually, instead of just the "what" of what sounds good, you start learning the "why."
Hey, absolutely! Actually, I started learning chords prior to scales. And only wrote about scales because they seemed to be the meta-skill that many others are derived from.
I'm still figuring out how precisely the circle of fifths is useful, someone feel free to chime in.
Piano is different than guitar because (from my limited knowledge) guitar songs are mostly based on chords while on the piano the chords are often broken up into individual notes, eliminating the need to memorize/remember specific chords/scales.