Because they are made for flat bar postures. It's like complaining that you can't put 26" wheels on a 29r because the geometry makes the BB too low. Uh.. Yep. They don't make em to take 26" wheels and, for the most part, they don't make em to take drop bars.

No, actually it DOES solve the problem. Just go down a size and the reach and stack will be what you are looking for.

Also, to say that a frame has excessive stack and reach for its size is a nonsensical statement. Stack and reach IS the size. It is like saying someone is tall for their height. If you find that all larges have a to big a stack and a reach, that means you should look at a medium.

What you are looking for is already out there you are just too set in your misinformation to know what to look for.

The reason I like drop bars is primarily for physical comfort, and to keep my center of gravity low. It's not to develop handling skills or go fast. I ride at a leisurely pace but over extended periods of time.

If you go rigid, go with one designed to be rigid.

If you want lightweight, the Giant Toughroad is really great. I have mine with 30mm rim and 2.15" tire on front and it is very smooth.

Or look at the Jones bike, the ultimate bike designed NOT for suspension. Fits 3.25" in rear and up to fattire in front if you want to be flexible.

Sounds like you are a candidate for a custom bike maker.

The manufacturers design and make bikes for the masses. Not just what one person thinks they want or need.

Here's a start. Prepare to lay down some $$$ and get put on the waiting list.

http://waltworks.com/

MTB frame design
 

The seat posts way out like Mr. Clem von Jones's Scott 29er make me cringe. The forces at work on that seatpost tube are magnified if the frame isn't triangulated by supporting seat stays near the top of the seatpost tube. This comment is for non suspended MTB's. Suspension helps to soften the forces at work on a long seat post out of a frame. I have seen rigid steel frames fail due to the seatpost loadings on the seatpost clamp or the tube itself. That said a MTB should have adequate clearance over the top bar to limit the frame from highsiding the rider on narrow trails with a steep side angle. If you get hung up on a top tube before your feet hit the ground you can fall. Tough choices but I like to see less seatpost extension out of frames. Having raced MTB's here in Northern California I saw all the early attempts to put drop bars on mountain bicycles and race them. For MTB racing the drop bars did not work out. Ease up on the harshness of the off roading and you get gravel roading and drop bars work great for that. I checked out the Jones website and that is a very cool bicycle. Big fat tires really don't need suspension unless you are racing and maybe not even then. I really like their ability to traverse sand, loose gravel, and other very hard to deal with riding surfaces and be comfortable at the same time.

Maybe things were different back in the day, but the exposed seat on that bike is not unusual at all by modern mtb standards and is a non-issue. Even on a HT. With the move towards longer and longer dropper posts, that amount of extension is expected and planned for with modern bikes. You just have to make sure you have enough post insertion.

Double post

I don't have experience with the modern style of MTB and these ultra long seatposts. I have broken a couple of steel frames with ultra long seatposts. The frames did not break where I expected but more toward the bottom bracket. The frames I broke were heavy duty and designed for longer seatposts. I've never broken a frame using short seatpost lengths. I'm over 220lbs and this may also explain why I worry about this type of design.

That is interesting that they broke further down near the bb. Not what I would have guessed.

Yea MTB was real popular in the 80s. Everyone, all 5 of those people, loved their rigid forks.

What happened to your "bike store"?

I tend to loose motivation to respond to sarcastic trolls

Sarcastic or truthful?

That is fine, nothing wrong with wanting drops. Just realize that many of the 29rs are built for flats and that you have to do a little investigating to find or create the right geometry to convert (or find one with drops already). You can't get mad at the industry that the conversion isn't a default proposition. It's the same with 26"mtb drop bar conversions. Doable, but you have to think about it.

Same thing that happens to most bike shop owners: he retired early with $millions.