Only by about 5% (Su-33UB), which might well mean wing loading didn't change at all compared to the basic Su-33 due to the weight increase driven by the new side-by-side cockpit section and the larger aerodynamic surfaces themselves. Bear in mind that the basic Su-33 is already better than the MiG-29K in this regard.
On the Su-27KM (note to readers unfamiliar with Sukhoi's designation mess: this was NOT a true Flanker-variant but a navalized Su-47!), wing area was quite a bit less - making FSW and interesting weight saving measure, same performance at lower area/weight. Though the real-world feasibility of the FSW concept has yet to be validated of course, and it would likely be a cost-prohibitive path to follow for a post-Soviet Russia.
That's just the point though - T/W ratio is a driver of aircraft empty weight (so is stealth)!
Consider the following thought experiment: let's take the F/A-18C and look at the changes we might need to make in order to turn it into a STOBAR aircraft still capable of carrying the same payload weight over the same range.
First of all, we'd need bigger engines to do away with catapult assistance -> higher empty weight (due to the engines themselves being heavier and structure beefed up to take the greater engine weight & thrust), even though the *ratio* of thrust to weight ends up improving.
To maintain the same fraction of fuel weight to total take-off weight and account for the bigger engines (to meet the same range spec), we now need to increase fuel capacity however. That means bigger internal tank volume as well as structural strengthening to withstand the greater loads, further pushing up weight.
That in turn means our wing loading is out of whack, we need more wing area -> yet more empty weight.
But wait! Now weight has grown to the point where we need even bigger engines, so return to the first point - rinse and repeat.
After a couple of iterations we'll be able to make ends meet again, but the resulting aircraft will be way heavier than (and look considerably different to) the F/A-18C we started out with, although it doesn't deliver more weapons or fly any further. All we've done is to get rid of the catapult, but weight is a slippery slope in this regard - we've only been able to succeed by, in essence, reducing the fraction of weapons weight to total take-off weight (and since weapons weight is constant, that meant increasing aircraft weight).
Such as?
Other than the considerable weight penalty to maintain the same payload/range (which is the root cause of the other drawbacks: more deck and hangar area required to handle the bulkier aircraft, greater fuel bunkerage needed to support the same number of sorties before the carrier needs replenishment), STOBAR actually looks pretty favourable. No catapults required (saving considerable development cost, ship mechanical complexity and ship operating cost), likely shorter launch cycle time (no catapult preparation), MUCH higher bring back weight than STOVL...
Time on station at a given distance from the carrier with a given number of missiles is driven by the same considerations as range with a given payload. While orbiting, the aircraft is still moving, even though it doesn't cover any distance - the optimum speed is slightly lower, but more fuel per weight still means more endurance in the same way that it means more range. What avionics does the F/A-18 lack in your opinion? It has a good look-down-shoot-down radar with track-while-scan capability, a data-link (recently) and can carry a comparable number of missiles:
This configuration has a very slightly better fuel fraction (0.322 to 0.318, accounting for a possible drag penalty of those dual launch rails) as a basic Su-33/J-15 with 10 MRAAM and 2 SRAAM.
