ChainsawAsh said:
I think the most that needs to be done is adding in a couple shots of AT-STs going ahead of the AT-ATs to take care of the Rebels in trenches. I've always wondered why they didn't do that - send the smaller AT-STs ahead to make way for the big AT-ATs.

SImple: budget. George and company no doubt wanted to do more, but being 1980 and the limits on technology and what money they had to spend, could only offer what we see. That doesn't mean anybody should overload the film with anything, but let's all remember the whole point of the SEs to begin with was Lucas' attempt to bring them "up to date".