I agree with you it definitely
looks better

I just found it didn't "mix" too well with liquids, at least in my case

Now I have a GT with leather and that doesn't give me that type of headache.
I used to have a 2007 SXT, which was "leather", but had the same kind of deal as my current one (GT), where the edges were vinyl/leatherette, and the main/inside parts/"panels" were leather - probably cost savings vs. making the whole just "leather". The only problem was, the vinyl started to crack and rip after a while, while the leather remained relatively soft.
I'm all in on leather, or at least leatherette! Growing up my dad usually had leather furniture in the house, so it was what I was used to. Nice and clean. My first car, even being a piece of junk old Explorer, had leather. My 2nd car did too being a vintage Jaguar. Then I bought a coupe Jeeps in a row with cloth... That stuff was the bane of my existence. After the 2nd one I decided I would never own another car that didn't have leather. Leatherette/vinyl is also acceptable.
It's just a cleanliness thing. Cloth, or fake suede stuff is disgusting in short order just from regular use, let alone spills or other accidents. Not worth it. I'm generally game for paying for real leather and the stuff that comes with, but I don't get why more companies don't offer leatherette in basic low end models. Sooo preferable to cloth, and if it's not bundled with 100 other features like real leather usually is it wouldn't make much of a cost difference. Heck it may be cheaper, I dunno. Plus I think most people perceive it as nicer too, because it's similar to leather. The newer leatherette is pretty convincing unless you know what to look for. Vinyl was basically standard stuff in the 60s, don't know why leatherette isn't now, especially since it's so much nicer than old school vinyl.
No, is not about costs.
I haven't seen a manufacturer who uses leather all around.
Leather doesn't wear good on the sides (around the seating area).
Uhhh, high end companies do. My dads 90s Jag was all real leather. My Jag that turned 50 this year (I sold it 9 months ago when I moved

) was all leather. Nice, thick leather at that. Pretty sure some BMWs and MBs I've been in were all leather, although I'll admit I didn't look for that specifically, no vinyl jumped out at me. Thinking about it I believe my Suburban is all real leather too, but I haven't given it a close look either.
As for the longevity thing... Not in my experience. On my old Jag in the drivers seat the spot where my butt went was completely torn up (Thank god for vintage style real sheepskin seat covers!), while the sides were barely messed up at all. On the passenger side the seat itself had a few small tears/split seams, and the sides were still 100% perfectly intact.
Those were original seats that were manufactured in 1971. I don't know the real chassis mileage on that car, but it was definitely in excess of 100K miles, and may have even rolled over and been over 200K. That kinda driving plus the age tells me leather holds up a heck of a lot better than the vinyl that cracks at under 100K on these vans. Maybe those other pieces do get a little more wear, but leather when properly oiled up can bend/stretch and last for many decades... Vinyl always cracks eventually, and usually after not all that long. So maybe using thicker leather on the sides could make sense, but vinyl will never be longer lasting than properly chosen and cared for leather.