Some thoughts:
If you enjoyed reading the 3e core books, you should enjoy reading the 5e books. The introductory sections of the Basic Rules (or PHB), if slowly enjoyed (rather than gobbled quickly) awaken that sense of wonder of first reading D&D rules back in editions of yore. In fact, I'd say that the books are more enjoyable when slowly read in your comfortable chair, rather than just scanned for data. In particular, the Monster Manual is the best MM since the 2e Monstrous Compendiums, hands down. And it has full color art--lots of it. It is worth reading it just for the D&D lore that they've captured (and in some cases reworked, but generally just expanded upon without invalidating). I'm surprised that no one brought up the large quantity of random tables in the DMG. There are a lot of tables in there for inspirational purposes that you could use in any edition of D&D or a fantasy game. I vote the DMG, as "5e book most likely to be useful for non-5e gaming," just on that basis.
You
will get inspiration as you read through the DMG and MM, and you should definitely get inspiration on characters from the PHB.
You are able to try it without buying it. How can this possibly be a bad thing? The Starter Set has a great adventure that is good for about 20 hours of play. Or you can even download one of the free adventures out there. I believe necromancer games has converted one to 5e.
Let me comment on this. "20 hours" seems to me more accurate if you don't role-play, ignore all sidequests, only play with Basic characters (there is nothing stopping you from using the options in the PHB for this adventure--it's exactly the same game rules), and run combat on a timer. I have a group of heavy role-players, and it has taken us about 20
sessions of 3-5 hours to cover all the included content (that's not including extra content I've thrown in that has added more sessions).
One other interesting concept is saving throws do not scale
I should probably point out for the OP's benefit that each character is proficient with two out of the six saving throws, and those saving throws
do scale.
I like art, and a nice layout always pleases me. But I don't think its ever really been the one thing that ever sold me on a book. Though if we could get some comics back into rulebooks as with 1st edition ADnD, that would be great.
If it weren't out of print I'd try to sell you on buying the Alpha Omega RPG (especially their monster manual) just for the art, and I'm probably coming from a philosophy similar to yours. Those are the only RPGs products I've bought primarily for the art, and I do not regret it, as the art and setting is outstanding and it is worth using the books with a different game system just to have the art and setting.