It might add to the impact of the full force of the Imperial legion entering onto the scene if we saw them actually arrive in large numbers with support vehicles and the like.

In the current version the Rebels sneek in and when they are captured and lead outside we see a medium force of troopers with a few AT-STs and a few bikes (not really that much more than would expect would have been at the base in the first place going by the size of the buildings around the landing pad and the nature of the project they are protecting.

If while the Rebels were in we had a sense of the approach of a thousand strong deployment of previously hidden troops and the associated equipment it would underline the threat in Palpatine's boast. Imagine the impact of seeing a large army crunching down the forest on their approach to finish off the "pitiful little band" of Rebels and match that with the excitment of having an equally surprising counter attack.

That coupled with evidence that the Ewoks were planning to attack the Imperials before the Rebels turned up (by showing they had already killed some troops) so the traps don't magically appear overnight and adding some evidence of the Rebels using equipment they brought with them on the Tydirium (which could be more if the ship was a captured Imperial transport ship and not just a shuttle). It would add tension, drama and credibility to the ground battle and enhance the mood of the other battles rather than detract from them.

It might even be fun to have a few more Wookees in the strike team by pinching a few from ROTS (Chewie can't be the only Rebel Wookee and it would be a nice nod to the original intent of the battle).

The ground battles in the other Star Wars films had approaches which cranked up suspence (ESB, TPM) and large reveals of the forces involved (AOTC, ESB).

Something like that in ROTJ would really raise the bar for the finale of the saga.