not really important but i don't see why not since the whole point of html logging was to make it prettier

I think Plus! logs what it sees in the conversation windows so for the emoticons (winks, ink messages etc) it takes a snapshot of them and creates an image file with that snapshot to use in the logs. But to be able to log the animated emoticons, it needs the original gif files but it doesn't track those files which are found in the user's Messenger cache folder to insert in the log file.

yeah thats exactly right.. so maybe in future revisions plus is able to extract the anigifs from the cache and put them in the log.. perhaps in it's original size too (for some oversized emoticons which get resized automatically)

It's not always that simple. For example, your contacts emoticons could have been cleared from the cache before plus updates the logs (unlikely, but I suppose it's possible)