A few things to remember aswell wolverine...
Your Army doesn't just have an ATTACK value, and a DEFENCE value. It also has a HIT POINTS value.
Just like the real conflict, you need a little bit of everything to win well. Otherwise, everything has it's counter, or, has no purpose.
I used to be AGAINST buying artillery as well, but their counter attack capabilities cannot be denied, and I also don't have to leave tanks behind on the front lines, if I can use artillery.
Most A&A units DEFEND better than they attack, and it's important to remember that to move an army forward, you want to be in such a position, that your enemies counter attack won't destroy you.
in building defensively, which you will have to consider if you ever want to win a game, a tank for $6, rolls at 3, vs 2 inf take two hits, and rolls 2 dice, collectively for $4.
For the SAME money, this gets exponentially worse...
2 tanks = 12, 2 hits, 6 defence power.
4 inf = 12, 4 hits, 8 defence power
See where this is going?
If you are GERMANY, with $48, and I am Russia with $36...
Germany has 8 tanks * 3 attack for 8 hits. 24 damage, roughly 4 hits
Russia has 12 infantry * 2 defence = 24 damage, roughly 4 hits.
Don't even make me calculate what happens to your tanks in the second round...
For 75% of the cost, the Russians can kill just as many units as you, whilst losing infantry to your tanks.
There's no denying that tanks are good, and you want some... and you also want to mix in some mechanized units, in case you get a chance to BREAKTHROUGH the enemy lines. Artillery is good, but too much is no good, you'll run out of infantry... it's all a balance my friend. You'll figure it out as you play the game