JackieChan largely speaks the truth about effects and causes for camping with no firinging in the charge.
The problem is, and will always be (given sufficient numbers in the lines) that it's too costly an affair to cover the last distance to melee to actually pull the battle back/make it into melee at all. With firing in the charge you give the enemy an incentive to stop reloading and spread out and counter charge rather than just shooting (strafing) fish in a barrel.
Hill camping is a bit awkward, but it's not inherently a problem to be honest. If you have the (valid) option of attacking them in melee it's simply a matter of going there and meleeing them. Contrary to popular belief terrain doesn't confer a tangible advantage to melee. Sure the different speed might throw you off, but it's the same for everyone, and if anything the slower speed will benefit the better person since they might live through one lucky stab and land two stabs themselves to kill the enemy.
Hillcamping turns into a problem when melee is not an option because a hill (crest and reverse slope too be exact) do confer an advantage to shooting. Which means that your option is to fight a literal uphill battle using shooting where all the odds are in the enemy's favour, or hillcamping yourself. Hillcamping yourself causes drawn out long and boring battles, and that is the problem. Not to mention that there is virtually no skill required to hillcamp, so luck will be the deciding factor of the battle.
Boring (patience based and) luck based battles seem hardly desirable for this type of event in my opinion.
Dressing the gaps does not necessarily need a rule either. A competent leader will know how to forcibly make the enemy dress the gaps, and as such it promotes more manouvering in shooty battles as well.