[JGZinv]

Yeah that would be something... a transport jammed through the main hanger on a ISD.... 

Well - perhaps the troop transports were intended to be used for boarding the
DeathStar II...  If it was supposed to be a minimally guarded station
under construction - a few hundred troops could take control and plant
charges at key points like the Endor ground crew planned to do.

20 MonCal's and the others listed would certainly make a nice defense
fleet if they were only buying time for the boarding team. Instead the transports
ended up being sitting ducks needing protection.

My ten cents on the matter...   

[chief1983]

I think that a slightly more plausible explanation is, if you don't bring them with you, where do you leave them?  They may have just thought the risk of leaving them unguarded was too much, and they would fare better staying with the main battle portion of the fleet.  But I think that having whatever added guns they could bring might have been part of that reasoning as well.  As far as a fireship goes, I think also loading the transports with high explosives would have enchanced the effect significantly.

[AlexG]

*coughcoughBastioncoughcough*

Hm. The transports could also have been to pick up prisoners from Endor after the battle was done. They probably presumed that there'd be a lot of troops with some fight still in them down there, and you can't just let them stay around, now can you?