One thing is for certain: as bowlers age, or have injuries in various parts of the body, a good slide length becomes a critical issue for these bowlers. The slide accomplishes a couple of things. First, it allows you to slowly and smoothly decelerate your approach, and secondly it works in conjunction with your ball timing. As long as you are sliding, you aren't committed to releasing the ball. Once you come to a full stop, then you are committed to release the ball, whether or not your armswing is in synch with everything else or not.
Age and injuries plague a lot of areas of the body, and the sudden jarring force of slamming to a stop on the approach may be more stress than certain body parts are happy with. In some cases, the need to slide is significant enough that the bowler must either be able to slide, or sit out on the sideline. Bowlers with slide knee injuries (waving my hand here, multiple times), hip problems, shoulder problems, spinal problems, and a whole host of other difficulties need to be able to slide a desirable amount so that they can unload the pressure of the approach and delivery. A 19 year old youngster might be able to get away with a plant and rip delivery, but a 49 year old bowler with knee problems might find that planting at the foul line takes him completely out of the game due to pain. I do see some older bowlers who don't slide, but these bowlers have made compensations in their approach and delivery in other ways to limit the stress on the body. I can think of one fellow in his '70's who bowls with me, and he simply walks slowly down the approach and gently lays the ball down on the lane as he lands on his slide foot....he has compensated by reducing his approach speed and significantly reducing his ball speed. So, you can't say that all older bowlers slide, but most of them prefer a longer slide for the stress reduction as well as the ball timing improvement.
Anything you can do to improve your slide to get what you feel comfortable with is a plus. Of course, some of the possibilities are against the rules (EZ Slide or baby powder on the approaches), but you have options such as the slide socks, Tru-Slide, Glide Slide, and variable sole/heel slide shoes. Somewhere in that combination of methods lies an answer for just about any situation. You don't have to live with tacky approaches, unless you fail to explore the possible remedies.