As the Game Designer, this is one question I had to face a lot !
First of all, yes it is technically possible to play the game without the miniatures, but it is not fun to do so. The game was designed to have the Software AND the miniatures together as a whole, so if you only play with the software, you will me missing some information: number of miniatures per unit, fight directions and the most important info: the global view of the game. That last point is the most important, because the software always ever show you one tile at a time (it is as if the game focuses on the current action).
The other part is in the game's dynamism: Without the software, the game would be another miniature wargame (with very cool rules :P) and without the miniatures, it would only be a dull videogame. Both put together gives a very unique and dynamic experience! Also, the density of miniatures in the same zone makes a difference for shooting and close combat and is much more palpable when you have it in front of you.
The last point is the simple fact that the software was entirely designed as a tool between two players... you can change all the parameters you want to make the game fits to any setting you want (change the board size or shape, play Day or Night, put any terrain feature wherever you want on the map, the game size and rules of engagements, etc.) so it wasn't designed as a videogame and is uninteresting on its own.
To conclude, I just want to specify that the current Kickstarter is intended for a Classical "Rulebook" version of the game and will be a complete standalone from the digital versions.
Both games will continue to be supported !!!
Hope this is convincing enough