1. What the value of your ground skill if you can't even take your opponent down?
2. If you have good take down skill and good body slam skill, can you skip your ground skill training? This clip shows may be you can.
1. your takedown skills can be quite medicore if you dont mind landing on the ground with your opponent, your takedown skill needs to be much higher than your opponents defense if you plan for him to land on the gorund and you to be standing.
If you figh an amazing wrestler it might be really hard to be better than him at throwing - but if you manage to pull guard on him you might have just nullified his standing game - and it might be sufficient to have 1 year of bjj experience if he has 0 to win.
2. of course you can, if you have a perfect spinning jump kick you can skip boxing, clinch, grappling throwing and ground. Will you risk not having a skill in certain distance at all? Is you other distance skill so perfect?
I would say its always worth investing some time in all kicking, punching, throwing and ground game - why would you skip ground game?