My complaint is that the "messages read and cleared" feature leaves a persistent cookie on that particular computer, not in your user account.
I consistently use three computers.
On my work computer I'll mark everything read on Friday afternoon before I leave.
I'll read throughout the weekend.
Yet, when I get in Monday morning, my work computer says "hey, you've not been on TFL since Friday, so you've not read anything!"
The exception to that is for threads in which I've replied. That seems to break that persistent cookie.
It's hugely annoying.
But, I can see why you're not bothered by it. Anyone who uses an iPhone has demonstrated he just aint too bright...