Yep, that was me.
The reasoning wasn't that we didn't like it and wanted to kill hidden features (as above, I loved it), but more that all things, even small or hidden ones, come with small and hidden cost, and cost is the end of large projects. It sounds a bit daft to many, but just having the code in the tree is a burden - tests run, translations need to be updated, and minor dependencies all over the place increase development costs persistently. For example, consider the staff who added the "audio indicator in tabs" functionality and how the presence of a separate tab system in the tree might cause them extra work, or how their work may inadvertently cause critical bugs in sidetabs that don't have an owner to fix it or care for it.
To keep Chrome nimble we attempt to cut and trim as much as we can, knowing that that annoys some. We don't always get this right, but it's better to aspire to do fewer things well than to be generally OK with crufty bits here and there.
I realize this explanation probably won't decrease the sadness, and you've probably heard something like it many times in the bug tracker, but if not, I hope it explains things a little.