Just what exactly is the formula? I started watching the show finally and I'm on season 2. It's alright, but what about this show has lead to it being such an influential pieace of work? I feel there's something about me that the show isn't quite connecting fully.
I think you're asking two different questions here.
For why the show influential, back when it aired there was honestly nothing like Twin Peaks. There was no TV shows that had such a large cast of characters you saw multiple perspectives through, there wasn't anything that went so back and forth from being oddly silly to darkly serious with contrasted tones, the camerawork was way above most other TV shows at the time, and it was a MAJOR pop culture hit, back when it aired its first season and up until the killer reveal it literally hit several countries by storm, notably America and Japan both were consumed by the show for a while. Everyone was talking about it, covering it, it was one of the first major 'water cooler talk' shows while people talked about their theories on characters, the weird scenes in the show, and the overall mystery in public places, at the office, etc., and it's gone on to inspire countless people in artistic fields, direct works, and techniques it used which were unheard of back then. Twin Peaks was largely influential due to what it did with television and the major success it found, giving it a lot of staying power in people's minds which has kept it relevant 25 years later.
Now for your personal feelings, noting is made for everyone. Twin Peaks I would best describe as a soap opera parody mixes with a supernatural murder mystery, except add an extra dosage of weirdness to it and in the shows second season especially an actually legitimately creepy surreal horror aspect begins to grow. It wasn't a perfect show by any means and the network realizing what a huge hit they had on their hands tried to take too much control over the project thinking they knew what was best for the show, but it was never intended to please all audiences. Many of the cast members acted on the show for their own reasons but none never really suspected the show would succeed, but it was a surprise smash hit even to many of them. But by the nature of the show it wasn't ever really made for a large audience, Lynch and Frost were stretching themselves after several projects had fallen through for both of them in the 80s and they lost deals to make their works due to studio failures, so they teamed up just to make something they wanted to make (after their original show project failed due to the network backing out, so they just wanted to make something together they wanted to make as they enjoyed working together).
However, Twin Peaks influence and the overall influence I think makes a LOT more sense if you've seen David Lunch's other films. Twin Peaks was the biggest pop culture phenomena of his works, so it's what most people name as influential, but I honestly think David Lynch as a whole with his works has been more influential than Twin Peaks individually has. If you watch his full discography, you'll be surprised how many other things in the last 20-30 years you've seen that have been inspired by his works in one way or another. He quite frankly tackled film, visual storytelling, and ambiguous storytelling in a way that is very unique to him that began to further influence others, and there's a number of scenes which he's produced which has inspired countless others, he has a strong talent to make very unusual but impacting scenes. Various scenes from Eraserhead, Blue Velvet, Elephant Man, Mullohland Drive, Lost Highway, and indeed Twin Peaks, among others, have found there way in various faucets of entertainment.