Adapting to casuals at the cost of optional longer battle durations. Thoughts?

Normally i'm not one to simplify something complex just because people cannot adapt or keep up, as it takes the fun out of my ideals. In my work-in-progress game, I require quick user turn command choices to make use of a bonus damage combo systems and powerful strategic abilities/skills. Like for example the player must enter their command (for one actor) within 5 seconds to keep a combo bonus of stacking 1.2x damage boost per combo hit.

Now because this game will probably be (in the future) played by mostly you RM peoples, I know well that many people here are...well...slow-reaction-planning casuals (no offense) according to various threads. So I had an idea, being able to disable the timer function at the cost of not getting the stackable 1.2x bonus damage (which can be a huge damage giver with a bit of strategy) It seems like a fair trade-off, better than nerfing the system itself which I want people to play with by default. My only concern is how big will the damage loss be. Encounter/boss length will mainly be based around having and making use of that bonus damage. Lack of bonus damage also means the player will take more overall damage in battles due to not winning as fast.

I am taking possible ideas on how to compensate for longer encounters (but not too much compensation) so that my casual players who don't use the turn timer / combo damage boosts can not get wrecked and have a more enjoyable experience.

(Once again, using the turn timer / combo damage boost is set to default,  and I also want casual players to attempt to use it)

P.S. simply lowering the damage of enemies/bosses if the system is disabled isn't an option since I have a difficulty script that already edits enemy stats. There would be compatibility issues.

I'd personally suggest not removing the bonus altogether, but maybe allowing a small bonus by default if the player chooses to disable the timed combo mechanic. However, with that mechanic active, there is potential to achieve a much higher bonus. Just a rough example. Say normally the attack damage is considered as 1. And perhaps the timed combo bonus can allow it to get higher like let's say up to 2x the damage, with a variety of stages in between 1x and 2x. But if the player chooses to disable it, then perhaps they can deal 1.3x the damage at all times, or whichever value you think will be fair.

Edit: Alternatively you can make an easier version of this timed combo mechanic, i.e. it might give a wider input window for people with slower reactions, so they have a fairly reasonable chance of getting some of those damage multipliers to apply.

I could possibly extend the time windows for the turn timer (default 10 seconds) and the combo availability (default 5 seconds), but it would clash with some special accessories that already increase those values. (which I plan to give it special strategic purposes) (15 second turn accessory and 8 second combo accessory)

I do like the idea of a smaller version of the combo damage bonus, maybe I can do 1.1x instead of 1.2x when the system is disabled. But I feel that it's not much differentiation between the two to the point where it really matters. It feels more natural and rewarding as a "play fast for the bonus or don't get it at all"

Isn't this just easy mode though?  What's wrong with making an easy mode that's actually easy to play?  You're not trying to get these two modes to be used by the same person, there's no need to balance it so that the action version is more attractive, the action element alone should do that.  Make each mode work within itself, don't worry so much about how they compare.

"Casuals" is probably the wrong word (I can't think of too many casuals who play RPGs, period), but aside from that, I think it's a good idea that you offer an option to disable the "button hits" system, since some people will just get tired of it after a little while, and some people, like you mentioned, just don't have the reflexes to nail it often enough.

Make sure that you aren't punishing the player for using the option to turn the system off.  If the combo system means damage will be somewhere between 1 and 2, whereas disabling the system will make it always 1, then you've failed as a designer.  Instead, do one of the following, or similar:

• Like Matseb mentioned, pick a number somewhere in the middle like 1.3 to use if the system is disabled.  Then, balance your game around that, and finally adjust the combo difficulty appropriately so average players will also be landing about 1.3 on average by using the combo system.
• Simply have the game pick a random number between 1 and 2 to multiply each attack/skill damage by while the combo system is disabled, aiming for a distribution that reflects an average player's ability to land combos.  This adds a nice bit of unpredictability to battle, but can get frustrating if those random numbers are the biggest factor in your success or failure in battle.
• Give the player the full benefit of the doubt when the system is disabled and set the multiplier to 2, similar to Sharm's suggestion of 'Easy Mode'... but adjust some other non-essential element (like tripling rare drops from monsters) while the system is enabled to reward players who use the combo system.

I was thinking something along these lines, but I currently have Difficulty settings in mind to handle extra exp/currency/drops given. Maybe I can find another factor somewhere to use.