Moreover, i have seen quite a number of 8051 trainer boards (i dont remember from which companies) tha have about exactly the same structure. Infact this was one of my inspirations and reasons to go with this design.
That lazy people exist does not mean you have to follow. Those keep making boards based on the old designs just because they are too lazy to make a new one.
There are boards (as well as books) that are sold as "new and fresh" although they were designed in 1992.
If someone has a pile of boards in stock, using the 8255, is he going to scrap them, or is he going to try to pawn them onto unsuspecting individuals - your guess.

Ok, i know that whatever board(s) are used for teaching OR whatever boards i worked upon in my days didnt need double writes to the 8255, but hey, even i never wanted to do the double writes ! It just s happens that in this particular wire-wrap design, i have to do it to make the darn things work. I am sure thsi will not be necessary in teh PCB version.

Be honest and say "I hope thsi will not be necessary in teh PCB version"

If you would give a link to the datasheet for the particular 8255 you use and give the FULL partnumber, (same for the '51) maybe someone could calculate the max xtal speed you can use

Erik