I'm not sure why pillar upgrades are considered less powerful than other upgrades. Some cards are better to upgrade, but many have -1 cost which is the same as a pillar. And since a pillar is more often going to be played first, a pillar upgrade is actually stronger. You really don't need multiple upgrades for it to be effective. You just need to draw the upgraded one (same chance as for any card you upgrade).
Plus pillars are extremely flexible. Any pillar will get used in more decks than most other cards.