It really depends on your army and what you plan on doing with it. The *only* time i've ever considered stripping jump packs off assault marines was while i was in theory-land designing an army intended to put loads and loads of marines on the field. The goal was basically 100 power-armored models in 1750 points. At which point assault marines without jump packs made sense, but not just from a 'more 15pt/model power armor' perspective.
In order to get the most out of jpackless assault marines, you need to consider historical infantry tactics and military theory, notably pre-napoleonic. The hardest part in waging warfare historically was getting your opponent to fight you. Running away was easier than pursuing, because ultimately the enemy had more to lose than you had to gain, and could (and probably did) drop extraneous mass like weapons and shields if necessary. This applied on a larger scale as well, because withdrawing was faster than having to relay orders to fight and arrange yourself into battle lines. Similarly, jpackless assault marines have a problem getting enemies to stand and fight. The solution was to bring enough force into the area of engagement to make retreat dangerous and likely to become trapped. So the solution to jpackless marines is to put enough bodies on the table that you can walk your opponent into a corner. This ultimately requires a large force of marines *all intent on moving forward*. (You can have some units standing back for long-range fire support, but most of your army needs to be applying pressure by attempting to surround the opponent, not just the assault marines). Of course, if your opponent doesn't try to run, you get to charge into him.
I'll note i advocate a line of tacticals in front of the assault marines to intercept any charges so the assault marines can counter-charge.
I believe the theory-list i made is indexed by Aerovyper as a DIY. (The Legionaires iirc, but i don't know if Aerovyper put names in his list. Check the stickies for Aerovyper's index). It may give you some ideas.