In Elite present BOTH ways to play are possible. WHY CHANGING?
Because one of the ways requires no tactical skill, no situational awareness, and just gives the player the chance to stay in the fight and win by only pressing a button - that's not skill reliant, but i-win-button dependant. If you can't depend on your ship being a duracell-battery able to recharge your shields several times over, you must decide when to fight and when to run, what targets to fight and which to refuse tangling with, and over all, you must decide when the situation demands you to run away, and when you can stay and fight even while being under heavy pressure.
If you don't have the Iwin Button avoiding fire becomes a first-class priority while with the button you can happily tank and fire back without even bothering to avoid return fire. With the iwin button you just need to press the button when your shields are down to one line and keep on fighting. Without it you're required to FIGHT, not to mindlessy TANK.
That's why. One way demands a degree of player skill, the other is just an EZmode for people who're too lazy to learn.
And on top of that because those things mean PVP is a freakin' never ending stalemate until someone depletes his Duracell reserves after maybe 15 minutes of meaningless combat. At which time he'll jump away anyway so that's a heck of a waste of everyone's time. And on top of the top of that, because the massive duracell arrays mean multirole ships which can load them are actually much better in combat than combat-dedicated designed ships which supposedly should be specialists at combat (paying a huge fee in short range, limited options, etc), yet are beaten by nominally less capable ships which have none of the other penalties. Which is just plain stupid under any light.
Need more reasons?
And BTW I agree, both RES and CZ areas give insane profits that in all due honesty should be seriously nerfed. Currently bountyhunting/combat offers profits well beyond most other activities short of trading with a Python/T7/Conda/T9. But a big part of that happens because currently bountyhunting/CZ farming is a joke given that having a neverending array of SCBs guarantees you can do it for hours without ever needing to go back to station literally farming millions with little effort and risk. Get rid of the never ending health potions, and most of that problem will go away (and even then I still think they're too profitable for the effort).