I watched the dive fight scene today in James Bond 007 Thunderball and noticed that...
It's quite an old movie. Diving has progressed considerably since then, with new kit standards and procedures.
Some people (as others have mentioned) still opt to dive without a BCD. For a properly weighted diver, especially when not requiring a thick (buoyant) exposure suit there is little need for a BCD except as surface floatation.
Same is true for wetsuits. If you're not cold, why would you wear one?
In movies you rarely if ever see divers with snorkels but check any PADI book or video and all scuba divers have a snorkel attached to the mask keeper even while 100 feet at depth.
PADI maintain a standard that students must be equipped with snorkels during training. This approach is illustrated during their DVD. I never quite worked out
why they had that standard - probably something to do with liability?!?
For wreck, tech and cave diving, PADI actually recommend
no snorkel - because it represents an entanglement hazard and/or interferes with long-hose regulator configurations (search the site for details on that).
Beyond PADI courses, the diver themselves get to decide their own equipment preferences. Most divers don't opt to wear a snorkel unless they have a specific need for it - primarily because they are planning an extended surface swim or maybe because surface conditions are rough (and they wish to preserve their air in their cylinder). Basically, it's a tool chosen if the task requires it. However, most divers do also find the snorkel to be an annoying distraction when fitted to the mask. Even if they do choose to carry one, then they might remove/replace it from the mask for the duration of the dive itself (reserving it for surface use only). It's useless when submerged.