I want to comment here regarding Simplified Chess, because similar issues can be leveled at Near Chess.  Near Chess drops the same rules, but keeps the games on an 8x8 board:
1. When pawns only move one space, then En Passant goes away.  This is one rule that makes chess extra complicated.
2. Castling is another rule that makes chess more complicated.  It was done to mobilize rooks and protect the King.  For a simplified game, it is fine to drop it.  If people have the problem with this, then go with Near Chess, which offers both back rows.  You can also play it on an 8x9 board if you like the odd number of rows. I prefer adding an Asian pawn capture forward when doing that though (in addition to capturing diagonally foward), as it gives the pawns a needed boost.  I will say here that not having a back row to retreat the rooks to does cause the board to need to be seven rows.
3. Capturing king instead of checkmate also makes it easier for a new person to learn.  It gets rid of stalemate.  People may think this ruins simple elegance, but I would argue there is a case for having this for new players.
4. These sons of Skirmish Chess aren't meant to solve anything short of being easier for people to learn.  There is some added bonuses (like reduced number of draws) but that isn't the intent.
5. There is complaints about the whole pawn promotion.  Well, there is a GOOD reason why the variant community should go with this.  If you are seriously looking to have variant pieces added to regular chess, the whole enabling pawns to become every piece on the board (even if there is not enough pieces), it grows to be an ever-larger disaster.  Do you want a flipped rook to become a 'Jester' piece that can represent any other piece on the board?  Guess what the rook does now.  It is that.  This rule works better with physical sets, AND helps the variant community.  It also makes a chess set no longer broken.  The rules in chess are broken today in regards to pieces.  If anyone things, 'oh we have electronic versions to play, why is this an issue?'  Try getting your non-variant players to log onto here to play.  Also, try to do it, if you want to start adding a bunch of variant pieces in real life.  Having rules that work with physical equipment is a good thing.  

I will say if Near Chess had happened, instead of what was done, or even Simplified Chess, all these complications wouldn't of been added to the game at all.  In this, my preference is for Near, but Simplified has merits.

Anyhow, my take will be, if you have problems with Simplified, then put castling back in and the pawn promotion as it is normally.  You can do Skirmish Chess on a 7 row board.  This should enable people to handle fine.

As for the simplifications people say 'ruin chess', may I suggest that you look again at Near Chess here.  Even without the complicated rules, the game holds its own, and you can do a mix of formations and rules, to be able to have a way that a person could eventually get familiar with the game.  And new players happen to like it by the way.  I bring up Near Chess in this post because I have been playing it.