I'm not sure if having eight high-pressure hydrazine engines (which must work in perfect sync) inches apart from the crew is safer than a classic launch escape tower with a single solid booster on top.

Do other types of rocket engines not need to be in perfect sync?

A classic launch escape system doesn't. It has several exhausts, but it's a single booster.

The original plan for Crew Dragon was to have it land with rockets like a rocket should, instead of with parachutes. They also wanted to have a design that could also land on Mars. Safety first NASA didn't allow that plan. Not sure if rockets are still powerful enough to do a powered landing coming from orbit. I hope so and that tourists will have the option of returning that way even if NASA astronauts don't.

They will not develop powered landing. SuperDraco or not, one of the main obstacles was the difficulty and risk of putting legs through the heatshield.

Smaller Dracos are used for in-orbit maneuvering. SuperDracos are now solely for launch abort. They could conceivably be used for an orbital maneuver requiring more delta-v than the fine-tuning the Dracos do, but at this point the only likely destination for Dragon is the ISS.

One advantage is that you avoid having to jettison the escape tower which would add some complexity and risk.

Also, the engines are designed for use in space during a normal mission and to be recovered. So in that configuration the crew would still need to be located close to a hydrazine thruster as a part of a normal flight.

> eight high-pressure hydrazine engines (which must work in perfect sync)

There's eight for redundancy, it's a fault-tolerant system.

There are 8 independent engines, IIRC, mounted two by two. I think they are controlled in pairs, one on each side of the craft so as to avoid an engine on one side not knowing its counterpart on the other side failed and forcing the capsule to spin instead of fly away from the faulty booster.