As a happy Legacy owner (x2) I have to chime in also.
I actually went through somewhat of the same dilemma when I was looking as I was looking at the Bobcat tractors and the Legacy.
The Bobcat CT120 at the time was around $ 17k with FEL and mid mount mower. A Legacy with Diesel and FEL was around the same cost.
I also looked a the CT230 at the time and I think that one came out at around $19k.
Both of the Bobcats are much bigger and heavier tractors than the Legacy and have higher lifting capacity. For me however where I need a good lawnmower they were simply too heavy. I have flat clay ground and a 3,000 lbs tractor will simply not work for mowing as it would leave big ruts in the ground. I would not be able to use a large tractor around my property without damaging the ground.
It would also be rather large to park in the garage and the attachments to it are expensive.
The Legacy was a much better fit for me. I think the big advantage here is the option of having the Legacy with a gas engine. This will shave around $ 3k off the price and will give you much the same performance (although maybe not longevity). Although I would love the diesel it is not worth that kind of money to me. And if my Kohler lasts its rated 2000 hours it will be around 40 years usage for me, so I am OK with that.
I think the market for the Legacy is for private people like me that needs a large lawn mower and like the option of using the FEL for landscaping projects. There are really no other tractors out that I am aware of that fits the small footprint of the Legacy or the versatility. (I think Kubota might have something but I think it is still larger). If this was to be used on a farm or commercially I agree that there may be more solid tractors available for near the same price. But they serce a different purpose.
The Legacy is not a full blown tractor and it was not really supposed to be one. That is what is good about it.
I really like that it is as easy to work on as a garden tractor as it has enabled me to by used at reasonable prices and fix them up to give me great some great equipment.
After selling two Craftsman GT5000 units with snowblower and snow blade, I was out $ 5k for the following setup:
2000 Legacy - 20 hp Kohler
54" mower deck
47" 2 stage snowblower
3 point hitch
Extra set of rims with Ag tires on
1999 Agco Allis 2025 (Legacy) - 25 hp Kohler
60" Mower deck
60" snow/dozer blade
Obviously I am biased as I have these two and love them.