The true reason Clu rebelled
Tron was standing at the edge of the mountain, looking out over the landscape of the new Grid. Some distance behind him, out of hearing range, stood Clu and Flynn. Clu looked at Tron’s back.
“I must say, Tron is quite an impressive Program, Flynn.”
“Yeah, he certainly is.”
“He has some quite… attractive physical attributes.”
“Are you perhaps referring to that well-shaped rear end of his?”
“Yes. It’s very… enticing.”
“Clu…”
“I wonder if…”
“Clu, I need you to focus on our work. I don’t want you to get distracted by ogling Tron.”
“I don’t see any harm in…”
Flynn stepped close to Clu, and put his hands on the Program’s shoulders. “Listen, I’m going to tell something I told you predecessor once, a long time ago, and I want you to take it to heart.” He looked into Clu’s eyes, making sure he had the Program’s undivided attention.
“No butts, Clu. That…” Flynn turned his head to look at Tron with a smile, and the frustrated Clu knew exactly where he was looking. “…is for Users.”
Flynn let go of Clu, and began swaggering towards Tron with obvious intentions. Clu’s eyes narrowed.
“Oh yeah?” he muttered as he looked at his creator. “We’ll just see about that.”

…

It was only half a cycle later that Flynn introduced the supposed “upgrade” to the System’s graphics.

Flynn’s own User eyes, in their lecherous greed, were privileged to go on ogling the Programs in all their original glory….

However…. the Programs suffered an enforced semi-blinding. A warping of their senses, no longer permitted to lay eyes upon what had been the Security Monitor’s most impressive attribute.

Even Tron himself, under this reprogramming, could not enjoy the sight or even the sensation of his own formerly lush render. To his own touch, his back and front were equally flat, to the point of confusion.

For the first, humiliating time in his existence, he found himself failing to notice when his previously form-hugging outfits were accidentally put on backwards.

Captured by Clu the final time, bound and tortured… Tron tried… he really, truly tried to resist the rectification.

But Clu, knowing the weaknesses of his victim down to the smallest line of code, made the final offer:

A rollback of Flynn’s cursed new graphic “features.”

A restoration of Tron’s dignity, his own precious backend code.

And that, for Tron… was the end.