Maybe I'm ignorant, but one could argue "Why was tce-load designed that way but not Apps?".
Also it's possible to update multiple extensions in one go by holding CTRL while selecting entries.
I definitely thought at one point "hmm.. why isn't this constantly available in every list of select-able entries?".
I don't have a definite opinion on that though. I mainly use Apps to look for an particular extension, read an info file, check for updates. For many extensions the loading is now done for me either by the OnDemand feature or by personal scripts (or manually via dmenu very quickly). However, I remember how it feels to use Tiny Core's GUI tools as a noob. I thought they were broken when I didn't know better.