Its a speed issue mostly. Like what has been said DB is kinda slow at 2D but it can be done. DBC is an Interpreted language (think of old GWBasic with more features) while DBPro is compiled....
Using DBC for 2D is slow because of how it works, while in 3D it can be faster because of how DirectX works.
Many slam DBC because of what it can't do, but for 3D and the price, its just fine. DBPro is better, faster, more features ..... but more money. Play with the demo and see what you want to do. Making a game is alot more than just Place a Tank here, Have Wizard 3 shoot fireballs at Tank 1 until destroyed....
There is Modeling (make the tank, wizard ...)
There are effects (Fire trail, exlosions....)
Sounds
Animations
And the map,level, and so on.
To make a game you'll need tools to do each of these things and expect to spend at least a month learning the basics of each tool.
Even if you use other peoples models,textures,sounds,effects...
you still need to know how they are made so you know what they can do and what to do with them. Don't think DB,DBPro,BB,BBPro have everything you need in one package.... they don't.
I'm not saying don't buy, I love making games, but know what your getting into. Like any fun hobby, the real expense is first setting it up, after that its almost free.. Like photography, setting up your darkroom can cost up to $3000, but after that, your film is free and devoloping costs almost nothing and you have a nice hobby.
Game making requires:
Modeling - $20
laguage - $20-100 depending on options
Textures - free-$1000 depending
Sound effects - free -$$$$
Music - free -$$$$
Time - lots and lots
Website - sorta free or low cost ($9?)
My setup:
MS3D - $20
DBC/DBPro/PB - $200 or so, have all three
2000 textures CD - $9 at office debot
Seemless texture maker - free version from DBC showcase
6000 sound effects - $9 at office debot
MagicWorld - Free version from All Seeing Eye
MTV music maker - $9 at fred meyer (discount games section)
Website - 100MB storeage for free provided by ISP provider
as long as I do not have comercial advertisements
on my site.
Best reason for having DBC - lots of free models. and cheap.