If your design decision is based purely off of a choice, an opinion - and the only thing it does is limit arbitrarily (your admission, its not a technical limit) then you are literally and I mean this as fully fully literally as I possibly can:
FUN DETECTED, FUN NERFED.
What I find funny about Dragonriding in the old world is how little I’m actually noticing that I can now do it.
I mounted up on my dragon to do some random runs to old instances and I didn’t even consciously notice I was doing it. My brain is already completely accepting of “yes, this is flying” and I have to stop and remind myself that I couldn’t do it a couple of days ago.
When I tried dragonriding on the PTR I felt I could notice the reduction in speed. So far on live I haven’t noticed it at all.
It’s as if I just sort of zone out until I reach my destination and my memory doesn’t bother to log the elapsed time.
My response to Blizzard “nerfing” Dragonriding by 15% in the Old World:
This is such a non-issue.
If you’re really that upset, unsub but give me all your gold first.
15% slower. is still much faster than normal flying and still solves the afk feel of old world travel.
what are we going to complain about next? 11.5 inch bread at Subway instead of 12 inch foot longs? 
Tbh I hardly noticed it was slower. It’s still pretty fast. And very nice to dragon ride through old content.
you can fly from SW to booty bay in like 45 seconds. why would being able to do it in 40 seconds be more “fun”?
No, it doesnt feel bad. You are just whining. End of discussion. You need to put on your big girl pants.
But they’re built for 705%? What’s 100% more?! It doesn’t make sense to me.
They adapted a feature for their new zone to make it work in old zones… and y’all still complaining. 
He stole 15% flight speed from each player so he can fly fast enough to crash into the sky and break it open again to find his wife in the Shadowlands
This player describes the issue pretty well and explains why people are annoyed by it:
And if blizzard is so intent on making travelling feel authentic to its original zones
Like please stop messing with flying. Every update blizzard does to flying just makes it feel worse.
This is exactly what I thought too… I thought there’s no way 705% is “perfectly fine” but 830% isn’t.
I want different devs for WoW, these ones are just mental
Because even at the 85% reduction you can fly from Stormwind to Booty Bay in the same time it takes you to fly from one end of Ohn’ahran Plains to the other. The old zones are about 25% of the size of Dragonflight zones if not smaller
Oh and this.
Question Answered.
/CloseThread
So obviously mental decision #1.
Secondly, there’s feedback here - the general consensus is this was NOT NECESSARY. PLEASE START LISTENING TO YOUR PLAYERS WHO PLAY THIS GAME. This will wind up ignored just like Zaralek Caverns feedback.
Why. Does. Blizzard. Not. Listen. To. It’s. PLAYERS
100%
It just feels so bad to have the devs constantly fix things that aren’t broken.
And the fix ALWAYS makes the system feel worse
I’ll be real, I don’t even notice the speed difference. It’s still faster than traditional flight.
So should we expect to see static flying receive a pretty hefty increase in speed?
You know because blizzard is so intent on making flying feel authentic to its original zones.
lol no they just don’t want people to FEEL like the old zones are super tiny which they are basically. It works, it worked with soar it’s just too fast for their liking.
Only a WoW player would see dragonriding added as a faster travel option over traditional flying and still complain that it’s ‘wasting time’ because it has a slight speed reduction. You really wanna waste time? Use traditional flying mounts instead. Are you for real?