Nope, not at all a waste of money. Unfortunately it's in the nature of science and technology that progress comes slowly and builds on what's gone before. You simply can't start with a fantastic mission / invention which does wondrous things and can never be improved upon. First steps are always limited. But the improvements and progress will not come without that initial first step.
Almost every scientific and engineering achievement in the history of mankind was of limited value when it first took place. I'm sure when the Wright brothers took their first few flights and the best they managed was 852 ft before crashing, someone shook their head and said 'what's the point in that? What a waste of time!'
Admittedly that didn't cost a fortune to do, so it didn't waste money, but ANY advanced scientific undertaking of this kind today does cost money, and the benefits are not always immediately apparent to everyone. But without taking steps such as this, our knowledge of space objects and space travel - and ultimately our ability to use space objects and space travel for our benefit - will never progress.
On a lighter note, it reminds me of that old joke: They say the wheel is the greatest invention in history. But the guy who invented the first wheel was no use to anyone except monocyclists - It was the guy who improved upon it by inventing the second wheel and an axle to go between them who made the breakthrough. :-)