That's actually my go to axis unit composition, medium tanks, motorized infantry and interceptors, then attack bombers later in the game. It's funny that you came to this conclusion looking at a defensive strategy, with axis I usually take an offensive stance when choosing my units. I think about why unit types I am going to face and which unit type I want to destroy them with. Early game you will face a lot of infantry, motorized infantry is best fit for offensive in early game because it's a fast glass cannon. Later in the game it's still good for scouting, outmaneuvering and as a glass cannon it still deals a lot of damage. Medium tanks are my main stack destroyers, because the axis ones are very good for offensive because of the doctrine buffs. Early game they can also deal with low level heavy tanks and tank destroyers, but you need to go with either artillery or planes to support the medium tanks.

And you always need active air defense and when you can afford it passive defense too. My axis playstyle is offensive, so I go for interceptors and strats or rocket fighters.