This ability does set the stats of the resurrected Pirate to 4/4, which may weaken some of the bigger targets, but for the most part, this is actually a positive, turning your aggressive early Pirates into legitimate threats later in the game
There are also creature-lands like Lair of the Hydra that have an activated ability that animates them into creatures, and some planeswalkers, including Gideon-type walkers like Gideon, Ally of Zendikar and Kaito, Bane of Nightmares, that have activated abilities or triggered abilities that let them become creatures
Lord of the Pit (Alpha Edition) $105,000 BGS Pristine 10 Why It's Valuable: One of the most feared monsters in early Magic
I didnt doubt that it would be fun, but I had assumed it wouldnt impact the game much, and would instead be a bridge between the phenomenal Shimmering Skies set and whatever comes next