Is this card nothing but a problem looking for a solution or is it actually a useful strategic tool?
Lets look at what corps typically spend doing:
Melange Mining Corp. - Preventing this is annoying, but won't cause them to shed any tears.
Purging Viruses - Now we are talking - lets say you've Parasited a big piece of Ice and they've let it tick down to 1 strength, thinking they would purge next turn, what about if you have built up a huge Medium and want to keep hammering them next turn. Even to keep a pair of Imps locked and loaded to wreck their HQ next turn. You can do a bit of damage with this card, assuming they don't have a Cyberdex Virus Suite on hand. What kind of seedy cards can you use to trigger Populist Rally? How about Wyldside, Scrubber or Street Peddler? Sadly Aesop's Pawnshop is too classy to be involved in this populist hoo-ha.
Triple Advancing a 3/2 Agenda they just installed in their scoring server. Another interesting situation where you might wish to delay them one turn until you can make your big play for the scoring remote. However Populist Rally will set you back 2, a card and a to delay them one turn. Keep in mind that this is wasted resources if they only installed a Caprice Nisei or Adonis Campaign in that server.
So it looks like there isn't that much that you can do to mess up the corp's plans with Populist Rally. Is it useless?
Fisk Investment Seminar then put some more cards in their hand with Leela Patel: Trained Pragmatist or Laramy Fisk: Savvy Investor. Now cut them down to only having on thier turn to deal with being 5 cards over their maximum hand size. They are going to be praying for Jackson Howard. This would be a good time to activate an Eden Shard too.
Speaking of the corp's maximum hand size, how about Valencia Estevez: The Angel of Cayambe, Investigative Journalism/Activist Support etc. and Itinerant Protesters? For even more fun you could combine this with Fisk Investment Seminar to really ruin their day.
EDIT for Salsette Island: Taking away a will also prevent the corp from using Jeeves in a lot of cases.