Unless you've studied the airport diagram, which is part of the airport's instrument approach charts, you may be caught unprepared. The letter B also reminds pilots that this airspace has big bucks, busy airspace, and jet blast, things that can discourage landing at a Class B airport or flying through the airspace. And there's a cost issue. Virtually all Class B airports charge landing and other fees. Class B airspace may also be crowded, and to mix large and small aircraft safely requires pilots and air traffic controllers to exercise extra diligence.
Wake turbulence is a likely factor, and on the ground, jet blast is a potential hazard.
Finally, if you don't meet the pilot certification and aircraft equipment requirements, flying into Class B airspace will put you afoul of the federal aviation regulations. Still, there are plenty of good reasons to visit a Class B airport. Perhaps you need to pick up or drop off friends or business associates so they can connect with commercial flights. Always associated with large cities, Class B airports often are convenient to numerous attractions and amenities. If you are in training for an instrument rating or airline transport pilot certificate, a Class B airport might be a perfect location to practice instrument approaches and procedures.