All the automated barrel producing machinery is set-up for handling 22" barrels most likely and I don't know at what point in the process the barrel gets rifled. It may not be cost effective to muck about changing the settings or mayber the machinery can't be changed. There is a lot more to the NEF barrel making process than just chopping off the barrel at whatever length you happen to like.
If Rem offered different barrel lengths in their accessory program it would quickly tell them WHAT barrel length for what caliber is the most popular. Trying to convince them to do it is the major fly in the pie.
I like long barrels and squeal like a stuck pig when people chop them off, because I know just how much velocity is lost between a 22-26" barrel and a 16" barrel, depending on the caliber as to the amount of loss per inch...BUT...In all reality, as far as hunting goes, a 22" barrel is a very good compromize...you don't loose too much velocity in any of the calibers and 22" is a very popular barrel length across the board in many non-magnum bolt guns.
A stub barrel or ANY barrel change isn't all that cost effective when considering the overall economy of the Handi unless you can do the work yourself...and even then the rough cost figure runs $150 - $250 for the least expensive A&B Midway or McGowen barrel and reamer rental, and that doesn't even count needing a donor barrel for the stub receiver. Kinda like trying to turn a VW into a Maserati by hanging a set of pipes on it and painting it red.

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But it's all fun.
Luck