Using the mouse for aiming the main gun is easy to get used to, but unfortunately the feel won't be realistic. For a more realistic, and therefore emmersive experience, the keyboard keys do a much better job thanks to the fact that coordination between traverse & elevation is then needed; just like with the real equipment.
That the mouse is used for aiming the main gun on tanks is really the only problem I have with the game at this point, and it will probably lead to me not playing as a tanker. I started a poll a while back to figure out what the preference of the community was on this issue as-well, where it turned out that 80% prefered the keyboard for control. But it's ok, from what I've seen so far I'll be too busy playing as infantry anyway, which btw looks absolutely fantastic.
Also there's no reason this small control issue can't be revised, and the developers will no doubt have a lot more time to look into this after the release. So let's see, it might get revised depending on what the vast majority feels like on this issue.