This couldn't be further from the truth because nowadays the bottom section can be such a variety of things that asking for anything that wasn't already available would be nearly impossible. One thing which sometimes strikes me as odd are people's desires to buy custom bunk bed designs. Most people however tend to ask for one that has storage spaces available below or room for a desk or a couch and so forth. Simply put, there are all of those designs and more out there if you take the time to look. This is almost always unnecessary because there are simply so many different types of bunk bed out there, that if you look hard enough you're bound to find what you want. The main real reason people ask is because they seem to assume what they're asking for is unusual and that most bunk beds are just a stand single bed on top of another with a ladder connecting them.

I think the only time that you should really be asking for a custom bunk bed to be designed for you is when you need one to fit a specific size.