The Tavern

pan is literally the most tedious and stupid place in the whole game. I thought crawl philosophy was to do away to tedious crap. None rune pan lvls should not be a thing.

It's been fixed in 0.21, in the sense that non-rune levels have been dramatically reduced. I think on average you now go through fewer levels per rune than for most other runes. In the game I finished yesterday, I went through 18 Pan levels for a grand total of 5 runes, which makes it less than four levels per rune.

Really I think Pan's main problem is the non-rune-level-sameness, if non rune level pan still could have 'themes' (take the monster set from one of the themed levels, for example) it'd probably make it feel less grindy, of course that would make the rune levels less special, ideally there'd be some themes that weren't the ones used for the rune levels.

Why? Do you want to remove Lair, Orc, Elf, Depths, Vaults 1-4, Snake 1-3, Swamp 1-3 etc. also?
Pan levels are scary, some characters get mutated, need to use consumables like teleportation/blinking/haste etc. Removing non-rune levels will make Pan much easier.

In my recent game, it took 23 lvls of pan to get all the runes. Now that isnt really longer than other rune branches, but it feels like it is. I think the main problem is the uncertainty of when you will get the rune maps and the fundamental difference in your mindset when you are in extended. For 1~3 rune branches, you are generally clearing the floors for safe exp and loot, but by extended you are more or less set with items and exp will come naturally even if you dont farm for it specifically. By comparison, Hell took about the same # of turns but didnt feel tedious at all because you know exactly where the goal is and dive down.

I know this is very subjective and wont convince everyone, but I think making pan similar to hell would be a good change.

You can do exactly the same in Pan: when you see a portal (which should not be too hard to find), you hop to the next level. At least as soon as you have the demonic rune, and you don't care for the experience or treasure you leave behind, there is absolutely no downside. If you do this, you should be arriving at a rune level within 5 minutes real time.

I do this whether I have the demonic rune or not. Imo it's best to always look for a portal to the next level and if you happen to come by the demonic rune (or get one of the special demonic rune levels), grab it. So far I've always found the demonic rune this way before getting all the guaranteed runes, without explicitly searching for it.

Just make the player spawn on top of a portal to the next Pan level.

Sure. And while we are at it, make all players begin the game in sight of all 15 runes and the Orb of Zot. It would take away so much tedium from the game.