DOS hasn't been "built in" to home versions of Windows since Windows XP. Windows ME was built on DOS, but prevented direct access to it in the way previous versions allowed. Enterprise versions of Windows have been based on the NT kernel since the mid-90s.
A large amount of older software is very difficult to use on newer versions of Windows. Windows XP is as old as Windows 95 was in 2005, so it doesn't count as "modern" by any stretch - unless, of course, someone was running Windows 95 on an Athlon 64 X2 in 2005. Windows Vista and Windows 7 have severe compatibility issues with programs written for versions of Windows prior to Windows 2000, and occasionally run into issues with those designed for 2000/XP.
Windows Mobile was dropped because it was considered a failure. It was, to a large degree, an attempt to place a desktop OS on a phone. It simply didn't work well.
Windows Phone 7, though still based on Windows CE, is a completely different platform that makes use of different APIs. Windows Phone 7's relation to Windows Mobile is no closer than Windows 7's relationship to Windows NT 4.0.
Your assertion that "Windows Phone is a fail because people said so" is also flawed. Everyone may have an opinion, but there is certainly a such thing as an invalid opinion. I, for example, am a mathematician. I am not a very creative individual. I see things very logically and algorithmically. I am also colorblind and have absolutely no education, interest, or background in fine art. I can assert that a piece of art is "a fail," but in the end, my opinion is meaningless because my opinion is uninformed and invalid.
The average salesperson has absolutely no idea that there's a difference between Windows Phone and Windows Mobile, not to mention people pushing technology generally have absolutely no idea what they're talking about. Around 2004, going to Best Buy would result in having an Intel Pentium 4-based PC pushed on you, completely ignoring the fact that AMD's offerings at that time were superior in every way.
A large amount of older software is very difficult to use on newer versions of Windows. Windows XP is as old as Windows 95 was in 2005, so it doesn't count as "modern" by any stretch - unless, of course, someone was running Windows 95 on an Athlon 64 X2 in 2005. Windows Vista and Windows 7 have severe compatibility issues with programs written for versions of Windows prior to Windows 2000, and occasionally run into issues with those designed for 2000/XP.
Windows Mobile was dropped because it was considered a failure. It was, to a large degree, an attempt to place a desktop OS on a phone. It simply didn't work well.
Windows Phone 7, though still based on Windows CE, is a completely different platform that makes use of different APIs. Windows Phone 7's relation to Windows Mobile is no closer than Windows 7's relationship to Windows NT 4.0.
Your assertion that "Windows Phone is a fail because people said so" is also flawed. Everyone may have an opinion, but there is certainly a such thing as an invalid opinion. I, for example, am a mathematician. I am not a very creative individual. I see things very logically and algorithmically. I am also colorblind and have absolutely no education, interest, or background in fine art. I can assert that a piece of art is "a fail," but in the end, my opinion is meaningless because my opinion is uninformed and invalid.
The average salesperson has absolutely no idea that there's a difference between Windows Phone and Windows Mobile, not to mention people pushing technology generally have absolutely no idea what they're talking about. Around 2004, going to Best Buy would result in having an Intel Pentium 4-based PC pushed on you, completely ignoring the fact that AMD's offerings at that time were superior in every way.