That's very interesting but I feel like Sega tried to make a game too big for a first entry into the series.... actually, not quite. Sonic 2 and 3 pull heavily from concepts made for Sonic 1 that didn't make it in.
For example, there were sketches of a mud gimmick for Green Hill Zone, potentially. They didn't put it in, but it's direct implementation is present in both Oil Ocean's oil and Marble Garden's mud.
Another example, we've seen that they were outright using S2 concept art for S3. For example...
This is concept art for Aquatic Ruin.
Now... look at this piece of concept art we KNOW was in effect in S3.
I'm pretty glad Sonic 2 and 3&K came to be as they were.