Let's face it, you'd be lucky if a new player grasps the concept of using infantry to capture an outpost. Understanding how to use bikes to attack a base such that they die and runners come out to capture the outpost? Not happening. Bikes have no business being on the default loadout.
This was not the intended purpose of bikes when they were first created. It's a secondary purpose, so it's by no means the only reason you should use bikes. They were originally created to be a quick unit used to run past or distract defenses, and keep the enemy on their toes because they would continually peck an undefended fortress, requiring the opponents to run back and see what's going on.
It's only been a recent addition into the game that they drop Runners, and their value has gone way up once they could be used to capture bases effectively, but that's really only for Tangos. Zippers are not as effective, and that is the only bike available by default.
The default loadout has a wide variety of units, allowing you to experiment with each one before deciding what you like, what you don't like, and what you want to buy next. The tutorial explains how to capture bases using infantry, so any new player should have the concept grasped already.
I am making a proposition to the developers to raise the money cost of bikes now that they have a new function (capturing bases by dropping runners), making Tango captures more of a risk.
Shooting ground units from air
Players try to shoot tanks or landed enemy mechs while still flying. This may be because of the way airmechs change flying height based on terrain, they can sometimes shoot streams of bullets that look like they hit the target.
I would suggest colouring air-to-air weapons a specific consistent colour (the pink beams that the neo uses would work) and have a separate colour for ground-to-ground attacks (the current striker weapons are fine for this).
This is something that can be covered and explained in the tutorial. Have the player shoot at a tank from air and make the tutorial say "See, this doesn't work. Now turn into ground form". That's all that's needed. Solutions not based on color should ALWAYS be the first solution. Changing the colors too much can provide extremely game breaking side effects for colorblind players. Take it from somebody who's been working with game developers for a long time, and is also colorblind. Tiny changes that seem okay can make the game almost impossible to play if you're colorblind.
HAATs/Seekers shoot ground?
I think we're all aware of the disconnect between "anti-air" weapons shooting at a grounded unit. I think this can be solved by just renaming stuff in such a way that it makes more sense. For example we could call anti-airmech missiles heat-seeking missiles that only lock on to the power source of airmechs. And we could just call the HAAT an anti-airmech weapon rather than an anti-air weapon. I would like such anti-airmech weapons to draw a targeting laser from the unit to the airmech, that way its clear that they are shooting at you and not other units.
HAATs do half damage to ground mechs, but I do agree the terminology could be updated. The developers eventually want to introduce air units, and the HAAT and Seekers would be able to fire upon them, but the air units aren't going to be here any time soon.