When I talk to people about this I don't think they understand what it really is.
The creator Mike Ossmann is a security consultant. He hacks stuff for people. He previously released the Ubertooth one which was a SDR that allowed you to test bluetooth security. It was a pretty big success. WiFi makes up a ton of the airwaves around the country. It also happens to be a point in which companies often have penetration test ran. There are other services too like cell phones that are just as vulnerable as WiFi but due to hardware have been out of reach of your weekend hacker.
Cell phones have been on the receiving end of some late night MTN Dew filled attacks. A few years ago it was released in Vegas that while using a Ettus USRP (<$1000) you could create your own micro cell site and pass calls through and listen in and monitor all activity such as web traffic, phone calls, text messages and emails. Still an expensive option though.
Last year the same thing was demonstrated by a group using a Verizon micro cell site that retails for $200 and is used to give people cell coverage by routing calls (encrypted) over the internet. The group where able to bypass some geeky stuff and do the same as the Ettus guys. They didn't publish a how-to, instead they told Verizon how they did it so that Verizon could fix it. That is called responsible disclosure and is a huge part of the "hacker" community.
Hackers (hence the name HackRF) are the driving force behind the HackRF. To them it is so much more than chasing a DX square or talking about hips and weather. There is a good chance that in the future, technology you use everyday (like cell phones) will improve directly because of the HackRF. Just like the Ettus USRP was able to demonstrate there are ways to exploit vulnerabilities if you have the money and the smarts. Smarts is not the main issue, usually it is the money. This puts a new level of technology in the hands of smart individuals that could not have afforded the capabilities in the past.
As hams we hear a "new cheap SDR" we think it has to work for us. It will not be a turn key radio like you can purchase form the big 3, but then again that is not what it was intended for. If you attach an up-converter to it you will be capable to view almost the entire bandwidth of HF. So 40m to 10m or 80m to 15m. Think about how that can help with DX spotting or propagation reporting!
There is also the whole other side to it where it is "open source". All the blue prints, plans, specs everything is available to you (for free). If you wanted you could download the plans and build one yourself. This is a huge help to the people writing the software because now they know the best way to interact with the hardware. Look at the RTL SDR, a couple years ago it was just a cool trick, now it is a genuine SDR that has a ton of applications. And think that is with a $20 TV tuner, what do you think that community will do with the HackRF?
I just typed all this on my IBM Model M and I think I am about to drive my wife crazy with clickity clackiting. Don't write off the HackRF because it is low power or geared to VHF/UHF it will be a great tool for the RF community and in the future you will really see it grow.