why does my iphone take so long to turn back on when the battery runs out?

Ok, granted, I am guilty of not always plugging my iphone in when it gives me the low battery warning. But why does it take SOOOO long to get enough charge to turn back on? If apple is taking suggestions, then my suggestion is that you should just be able to plug it in and it should be ready to use within a minute, like other cell phones. I've had my battery die mid phone call, and then had to wait for it to get enough charge to call back. I know its maybe only about 5-7 minutes but that seems like forever to return a dropped call. Does this happen to anyone else or is something wrong with my phone? Any suggestions?