Syed: to me it makes complete sense in terms of the Xojo language (hiding all the memory details for the developer). As Mars has mentioned in this thread, structures where introduced to simplify the creation of memory blocks for the following cases:
If you want to fiddle around with the memory in another way, just use MemoryBlocks. You can subclass MemoryBlock and add getters, setters and methods to create exactly what you need.