Wyndstar's ideal is not a very good one IMO. It would encourage even more micromanagement of the tax slider. You don't want to add game mechanics that add to micromanagement without dire need. It makes the game take longer to play optimally, and makes it generally more tedious, and less fun.
Frankly the only real cause to enact it over just the average is either a selfish desire to maitain part of the old exploits, or a rather tenuous argument about realism.
First off, assuming "weeks' in Galciv are in fact weeks (which seems frankly rediculous to me from a realism standpoint) people are not going to care you passed a bill to lower taxes a week before the election. Most of them probably wouldn't even know yet. People don't generally care too much about tax cuts until after they recieve them. Thus if we were going to be really realistic it might be best to have the morale change a year or six months later (or whatever tax schedule these fictional citizens are supposedly on (see its already getting rediculous)). These are incredibly abrstract mechanics symbolizing a lot of different things. Moreover what government in history is changing taxes week to week anyway?
And while it has been shown people have fairly short political memories in some senses, they also aren't completely stupid and a government which raised taxes immediately after every election would become very unpopular. People don't like to be made fools of.
The only real reason to opt for Wydstar's system over just using the the average morale value is so that people can continue to "game" the morale and not pay the full electoral costs of their tax settings. I don't see that as a virtue at all.
You should have to pay the cost of your tax settings. PERIOD.
This isn't a game about micromanaging a political campaign, its a 4X strategy game. One that already has a full case of micromanagementitis. You could take out probably 50% of the clicking in this game and keep 95% of the gameplay if you put a little effort into it. It would also take 2/3s as long to play too.
Personally I don't see why you should be able to adjust the tax slider at all except once per election. It would be more realistic (not that that matters greatly as I mentioned, gameplay rules all in a game like this), and more importantly, it would make players plan ahead. Do you plan on extra needed population growth, is there anything that might adversely effect morale? You would have more realistic tradeoffs between running a very tight moale status and losing the next election. It would encourage people to leave a surplus margin for the unforseen. Kind of like real life.
At this point msot anything which reduces play power is going to make the game more fun and more challenging for people.