If they did more damage or something it might encourage the player to kill them all.

At this stage players are at 3 hearts and these are doing 0.5 damage, reducing the necessary hits from 6 to 3 would be pretty extreme.
The one thing I had considered was forcing you to have to kill them all one time in order for the entrance + exit doors to open.

Killing to open doors was also fairly common on Classic. It should also make players realize that killing those guys chasing you actually have a purpose if they think they are just level decorations.

Hey, maybe a new tileset will help Classic get more players

There ya go.

If you're referring to the present time there is absolutely no worries about playercount on what is an Under Construction server, if you mean going forward I wouldn't be opposed to there being specific parts of the original tileset improved, overall it is a much more appropriate tileset for the adventure theme than the modern one, an entirely new one could possibly be too drastic.
Still I wouldn't worry about it too much as it's really the gameplay itself that is going to have by far the most effect on attracting players.

The tileset is fine...

No, but nice try.

You're joking, right?

A new tileset totally helped iPhone Classic. It looks awesome... now...

Exactly...

I think he's making a joke out of the fact that Stefan took his arguably good tileset from the public tiles thread and mixed it with stuff from the New World project which several people feel looks awful or atleast conflicts with the style.

The reason Stefan decided to do this in his own words was "I don't want people saying Graal is just a Zelda ripoff", which is exactly what Classic/Original Graal was.