Here is an article addressing some of the concerns about offshore drilling in the Gulf of Mexico.
Offshore oil platforms have operated for decades at the Flower Garden Reef. Here is more on this reef, off the Texas/Louisiana coast. The benefits of rigs to certain organisms are described here. Basically, rigs create new vertical habitats for organisms that must attach to some sort of structure. Once these attaching organisms are established, other organisms are attracted to the area. From the following link:
..."Natural structure and hard bottom are rare in the Gulf of Mexico where the bottom is pretty much a vast featureless plain of mud and sand. Where structure does occur, natural or otherwise, it is like an oasis in a desert. Virtual gardens of sessile (permanently attached) invertebrates like barnacles, corals, sponges, clams, anemones, bryozoans and hydroids quickly attach to every available surface and in every nook and cranny. "...
When the well (or wells) "plays out", removing the rig structure would damage the established reef organisms and disrupt the system. So a program was established to leave the structures in place (below a certain depth) and use the rig housing as additional structure for reef growth.
Rigs-to-Reefs program. From this website:
..."Since 1990, cooperating oil and gas companies have donated more than 64 obsolete petroleum platforms and contributed one half of the savings realized by reefing their rigs to the Artificial Reef Fund. These dedicated funds allow the Program to be relatively self-sufficient and finance research, administration, maintenance, liability coverage and construction of new artificial reefs."...
It is possible that the corals and other organisms in this area (SE of Galveston) are simply hardier, due to the natural oil seeps in the bottom of the Gulf. Whether or not reef organisms, in other areas, would "welcome" oil rigs might be debateable, but the record looks good. Imagine the disruptive scenario when a well plays out after decades and an emotion-driven demand is made for a total removal of the structure, even that portion well-below the wave base. Or imagine the damage done if the oil companies are not allowed a tax write-off for the abandoned rig.
These benefits are brought about by the free-market system and the sensible give-and-take regarding governments and their regulations. None of this is to suggest that these endeavors are risk-free (that world doesn't exist), but risks can be managed and minimized.
Our oil companies do listen to public concerns, but sometimes it takes years to find a solution to address the public concerns. Government-owned firms of China, Cuba, or Venezuela may not find Public Relations to be a priority.