why do you think sega keeps making ports/versions of classic sonic games instead of just porting the mobile ports to consoles , like sonic 1 and 2 have atleast 4 ways to play it on modern systems yet none of them are the mobile port wouldnt be easier to just port that version instead of making yet another version of these games ??
There are a lot of different reasons.
For one, those mobile ports were written in something called "The Retro Engine." Retro Engine is proprietary code, and Sega may not have easy access to that. I don't know about their archival policies or contractual stuff, but it may not have been their responsibility to have that raw source code on hand. They would have to contact Evening Star/Christian Whitehead for it.
Depending on how Retro Engine is written, they would need to consult Christian Whitehead and probably even Simon Thomley about their work on it, which then costs time and money and maybe they aren't available to offer their services at that specific point in time.
They also almost exclusively speak English, which, depending on which branch of Sega is spearheading the effort, presents another very large barrier. If the person at Sega heading up this project can't speak English (or doesn't like speaking English), they are going to avoid contacting English-speaking developers. That would add extra time, extra hassle, and extra cost.
On the other hand, most of the recent Classic Sonic re-releases have been handled by M2. That's a company local to Japan, they've worked with Sega for literal decades (since the 16-bit era), and they're deeply familiar with the inner workings of the Genesis. At this point, they straight up have Sega Genesis emulator code just lying around, ready to go, basically all the time now (M2 calls it their "GigaDrive" emulator).
It is faster, easier, cheaper, and less effort to just have M2 do it again.
And, for what it's worth, M2 does good work. They are basically Japan's gold standard in emulator development.
If we don't get M2, it's usually for something like the Genesis Classics Collection, a project by Sega of Europe, which covers way more than just the Sonic games. They developed their own in-house emulator for that, not related to M2's GigaDrive at all, and it is kind of bad. But, they wanted something they could just plug Genesis ROMs in to without a fuss (something that isn't necessarily possible with GigaDrive, and there's also that language barrier again).
Most fan-made emulators are covered under open source licensing agreements that makes them difficult to use for commercial projects. Fan-made emulators are also labors of love that get perfected over the course of years, sometimes even decades. An in-house coder at Sega has to deal with limited budgets and limited time frames, so their emulators are always going to be a bit crap just by the nature of the project and the structure of the corporation.
But it's all about the cards they've been dealt.
