I meant design wise, but yeah, it doesn't match his personality.
Tails was mean to be young, inexperience(
Also that is why he can't go super without Super Emeralds), sweet-natured and humble, he is looking like the average sidekick without any super powers.
Whoa. Whoa. Hold it right there.
1 - Its been confirmed that Sonic 2D era was roughly... what... 5-10 years prior to Sonic Adventure I think it was? It's been noted that Sonic "Looked Younger" in his '2D' model during generations.
2 - This means that over these years, leading up to Tails being able to stand mano e mano with technologically and combat-wise with Eggman. He's no longer
inexperienced in the least.
3 - Thanks to his growing up, he's a little more show offy and being able to stand on par with Eggman a few time's boosted his self esteem and pride, making him less humble than before.
4 - Tails' schticks are his flight and his intelligence. His speed's impressive but not that much. In this case he's perfectly aligned with his growth, seeing as he's shown a fairly incredible intelligence over the series and ever increasing it. However as he isn't that fast he relies on his tech to make up for it to keep up with being able to support sonic.
Now, back to #1 - Sonic's grown up, he's grown taller, more lithe. This isn't a design travesty, he's become less and less 'fat' over time. As for stick levels, that's a design choice.
Knuckle's upper body I'm iffy about, but it does catch that he's especially strong in upper body since he's constantly digging like a boss. Although it could use some deflation... some.