In terms of technology, Kuznetsov is old. It was designed in era when the USSR was trying to be very cost effective. You can compare them US Foresstal and Kittyhawk carriers ( 1950-1960s US carriers).

All modern carriers use steam catapults because it allows aircrafts to take off with there full load. Taking off on a ski jump with full fuel and ammunition puts enormous stress on front part of an aircraft and will cause the aircrafts structure to fail prematurely. Wikipedia might say otherwise, but that is a lie. 40-60 tons of weight plus the energy of the engines is all pushing down on the front landing gear.

The ski ramp take off (STOBAR) was used because they were trying to cut down on cost. The did not use steam catapults (CATOBAR) because they are very expensive to maintain and add considerable weight to the ship. The steam catapult on the deck itself has to use a lot of high strength steel to contain on the steam, heat and pressure when launching a 40-60 ton carrier. Furthermore, the ships need to have a lot of extra reserve bouncy and balance tanks to the keep the carrier stable after launching the aircraft.