Thought on signatures...

Size limitation's point is to speed up the loading of the pages, for all users. You might think that your 10/10 connection "is fast enough". It isn't. If a page contains 25 messages, each from a different user, everybody having a 50kb image, you load up the page for the first time and that means 25 different HTTP connections to be made by your browser, each pulling 50kb of data (plus HTTP headers), total of 1.2 megabytes.

Now, add the fact that most browsers (including Firefox)

a) by default, wont download more than 4-10 files at the same time for page, rest of the stuff need to go to queue

b) wont be able to render the page _AT ALL_ until all images -- that don't have set-by-page width and height known -- have loaded.

And for regular users, sure, it's probably fine -- you have our CSS files and navigational images already stored in your browser's cache. But according to many, many, many trials and tests, if you push the page's loading time from, say 1 second, to 5 seconds, 25% of people leave the site immediately. And even for the remaining portion, the user experience is already spoiled.

And another reason for not allowing larger sig files is the rise of mobile web -- 10 years after it was officially launched, mobile use of Internet is finally on rise, helped by fast phone platforms, good browsers and fixed-cost monthly data packages. Even with fixed-cost monthly data plan, 3G isn't very fast. And it has much bigger "lag" than wired net has -- thus, each request for each image takes its own time to initiate. And most people don't want to turn images off -- that cripples the user experience by making the site look ugly -- they just don't want not-needed-for-and-not-required images to be gone

As an addendum, I've been considering to hide the sigs completely for not-logged-in users, for the reasons mentioned before.