For me, it is always about what I need. Even though it is not guaranteed to get all the parts necessary to build a minibike or a motorcycle, I will take the kit if I
- Don't have wheels and need them (guaranteed to get 2 from the bikes, 3 from the gyro, and 4 from the 4x4)
- Have a chance to get what I need on the remaining two items
I don't feel that we need to have a guarantee to get all the parts just because we took the bundle as a mission reward. There are ways to get to the motorized vehicles besides getting a bundle that has all the parts we would need
- Loot drops for the parts
- Sold by traders
- Loot drops for recipes
- Unlock the recipes via the Grease Monkey perk line
The nail gun is always a quality of life improvement for me, but I never felt the need to go get it right away if I already have or can make a hammer myself.
One thing about the these bundles is that you can have multiple chances of getting it. Since you now have to clear out lower tier quests for new (different) traders, you have another opportunity of selecting the minibike kit if it is offered to you after completing the T1 quests for that new trader.
The only thing is that (from a quest standpoint) those are the only opportunities and you have to be lucky twice (once to have it offered and once to have the parts inside that you need). One thing you could do is offer it as a chance in completing the higher tier mission rewards. So for example, the minibike bundle could be offered as a T3 mission reward since it is one of the reward options once you completed 7 T2 quests for the trader.
However, none of this would be acceptable if one wants a guarantee to get all the parts.