The first two Special Holiday themed events focused on fancy customization items, but when you think about it Halloween is about dressing up and the Holidays are about decorating so the customizations make a lot of sense there.
When most people think about St Patrick's Day you think Leprechauns and Gold so while the previous two events could give the expectation of more customizations, Gold also makes just as much sense. While a goofy hat might be nice to have I'll accept the coins as well to help me inch closer to completing my wardrobe.
Keep in mind that the average player is under Rank 2500, with a whole lot who are still under Rank 1000 and the Quests and events will always be targeted at the average player as opposed to players who are closing in on maximum Player Rank, have all the characters and have nearly every customizations. For those of us topping out like that there's not much that remains to be offered and as entitled as many players may feel there is a definite lifespan assigned to new content roll outs and expansions and PvZGW2 has hit it, but despite that fact I still find the game fun and will likely continue to invest hundreds of more hours into it for the next year at least.