When I listen to the various pipe tunes, the regulators feature rather insignificantly on the Uilleann pipes. In some tunes it seems that they’re thrown in at the end just to let you know that they have them too. Do any tunes or players give them a more prominent role?
Richard L O’Mealy would use them very prominently to keep the time (he’d during faster tunes just tap the beats very shortly). Leo Rowsome quite oftenly played them all through tunes in very varied ways, combining different techniques. Seamus Ennis would also use his regulators a lot, not in the least during his playing of airs, but using it to highlight certain parts of tunes. And Paddy Keenan. And Willie Clancy. And Liam O’Flynn. And Mick O’Brien. And… and… and countless others, the list could go on to be very long and with more thouroughly analyzed in regards to techniques and variation by people who know a lot more about this than I do (hell, I haven’t even begun pondering regs yet, and won’t for at least several years). So in the end, I wonder which pipers you’ve listened to and how much attention you have been paying, because a lot of pipers who are generally considered influential and skilled really do use their regs quite a bit.
Regulators are harder to arrange if the pipers is accompanied by other musicians (eg. guitar) so pipers who are accompanied tend to use their regulators less. You should have a listen to some solo piping.
Examples of pipers who use their regulators extensively would include:
Seamus Ennis
Leo Rowsome
Johnny Doran
Patsey Touhy
And in more recent times:
Mick O’Brien
Paddy Keenan
Brian McNamara
David Power
Mikie Smyth
Look out for solo recordings of the above pipers and you’ll hear plenty of regulator playing.
Once you start playing the regs it’s hard to stop. They are frustrating, a pain and thoroughly addicting. They just add an entire new dimension to a tune.
Ronan Browne is the piper that convinced me to buy regulators, but I haven’t gotten them reeded and tuned to the rest of the set yet. He is awesome with the regs. I now have a 3 maker C 3/4 set (Mark Hillmann bag and bellows, Seth Gallagher chanter and regs, Pat Sky mainstock and drones).
Mikie Smith may have driven the nail in my uilleann coffin… 
Ronan is awesome. Wow, your set has a touch o’ class from some great names.
It’s a shame that I can’t do it justice. 
I know that feeling only too well my friend. Went in head first without a helmet. Tis time and money one needs plenty of for this beast.
I loved listening to Joey Abarta play his regs at the Seattle Tionol. He has really nice control.
I, however, have NO CONTROL and it sounds like c%$# when I play them. Takin’ it slowwww.
Kathleen
And here I was about to post that it was meeting Joey that convinced me I needed to get regulators as soon as possible. That was back on '08 when he was still going through his crazy polka phase… which I’m now finally getting!