Before we get an actual answer, can I know why this is important, my guess would be so you can bot the updates. Because an extra click is not that annoying. Chances are the programmers made the code more hidden (not choice option or any quest options) to avoid attempts to automate the process. Maybe it's just me but I think trying to macro this part, would make botting the upgrades way to easy.
Its not "important", its just convenient, so i can do several upgrades with one click. It gets pretty laggy when few people are on and I have to run several clients to do everything.