I am all for mixed cycling infrastructure. The best solutions come from carefully considering what is best for the particular situation and the needs of cyclists. Many people are for bike lanes regardless of the situation. The assumption is that if a city cares for its cyclists it will create bike lanes wherever cyclists ride. However, bike lanes can create a false impression of security; they can actually be more dangerous depending on the design and the context. Bike lanes also exist in large part to get cyclists out of the way of motorists who do not want to slow down and generally have no intention of seeing cyclists as equals on the road – not necessarily out of outright contempt, just out of not caring. Thus a bike lane can actually be created primarily for the wants of motorists, not for the needs of cyclists.
Here is a great video showing how a bike lane in NYC can become more of a liability than a solution:
In my opinion bike lanes should be considered as options (individually and legally). Cyclists who feel that bike lanes are unsafe should ride with the car traffic. Cyclists who are comfortable riding in traffic, and have the skills to do so, should probably take the road and ride with the traffic. This has numerous benefits and is known as vehicular cycling. Cyclists who like the perceived security of the bike lane, or who want to cycle very slowly, should probably use the bike lane, but with the realization that it also comes with its own hazards.