Not a reason to disapprove this. However, since it won't be implemented fast here is a trick that you should be aware.
Click multiple times over the link without waiting!!!
This will result in multiple levels in a single second.
The same practice works everywhere (voodoo, ship attributes, levels, captains, etc)
Here is why this happens:
1)Our game server needs about 0.02 seconds to do anything you command it (unless there is some artificial delay or something really long). You can spot the time our server needs for anything at the top bottom of your page.
2)The rest time, is time wasted over the internet for the result to come from our server to your computer. Mainly time spent on the various other servers of the internet and your isp to transfer the display data. These are usually a few seconds (1 to 3 perhaps).
3)So, a single click and wait, will increase the warehouse level by 1 and it will take you 3 seconds.
Multiple clicks and a single wait, can easily increase the warehouse 10fold or more in the same amount of time.
The best way to test this, is with a low level warehouse
Remember, click your left button multiple times over the same link (you can count but this will take more time, just mindlessly click a few times, then wait for the result). With time, you will become an expert in this.