Really? Mind if I ask why you don't like having the PCs surprise the enemy?
I've GMed something like 75% of my gaming career and I must say I find it fun and cool when the PCs outsmart my baddies and get the drop on them. Or indeed when my players outsmart me.
No. Surprising is ok, but I don´t like the rules.
We were asked, what should be different. I´d like the first round of combat to play differently.
Maybe I´d like the first turn of combat start with a surprise round, which only allows for a single action or move. A won initiative with surprise on top seems a bit too much for my tastes.
The playtest had a simple +20 to initiative on surprise, which was also ok.
My favourite however would be using all different kinds of modifiers for the first round of combat:
Surprised might be disadvantage on initiative. Using a ranged weapon might give advantage. And so on. Maybe +/- x modifiers.
I was tempted to use the modifiers in the DMG for round by round initative, but only for the first round and then cyclical initiative as normal.
I also don´t like the alert feat, and how you can´t be surprised, but maybe don´t even notice a threat.
But then, in most cases it works and my solutions are also wonky, so I stick to the normal rule and since we don´t have a character with alert anymore, most of my problems went away. I just like someone who gets paid for it to provide me rules I like more.
I generally think, stealth however has exactly as much rules as I need for theater of the mind. I think any rules that take the battlefield into account by default are a no go and usually cause more discussion than leaving it open to the DM. I would not mind some more defined stealth rules in the optional grid combat in the DMG.
But when we are at it, I´d think passive perception or passive checks as hey are used should go the way of the dodo. For all reactive actions, I´d like saving throws to be used. For passive perception, I´d probably stick to a class based value that might be modified by wisdom, but does not have to.