Although the application you created this hour was simple in appearance, it should have given you a good overview of how ADO.NET within the .NET Framework is designed. Microsoft realized the importance of data access, not just locally on a client's system, but also in networking environments, including the Internet. In some instances, a previous design just doesn't fit with the current technological demands in place. ADO is such an example. It's sometimes better to redesign a technology than to try and make it fit. So as not to leave out the developers who are familiar with an already established technology, Microsoft made the decision to support the older method.
The disconnected client scenario is something that will show up again and again in the future. As data connections become faster and cheaper, it makes sense to store data at a central location rather than replicate it across several clients. As with most other technologies, design is important. A well-designed application can never hurt you. Not only will it generally lead to fewer defects, it will also lead to lower costs due to less maintenance. The design decision for data-access methods is as important a decision as any other technology out there.