The reason why uploads are exceeding the limit is because of the language table - it serves as a phrase cache. If you open it in phpMyAdmin you'll see that the phrasegroup_<x> columns hold very large arrays.
The more products you install, the more phrases need to be added. When it eventually tips over a certain size, like 1 MB for some shared hosts, it becomes impossible for you to install any more products.
It's quite impossible to fix this on our end - you have to either switch to a less restrictive host or uninstall some large plugins that has lots of phrases in order to make room for more.