First of all, I am not responding to the imbecile OP. I'm just rambling about transportation methods for the 3 people on this board who don't already know, understand, and agree with what I'm about to say.
A subway and a lightrail and busses are three different transportation methods used for different things. Subways are for rapid, high density, and relatively long distance transportation through areas where ground space is too valuable to take it up with a grade separated above ground rail line. Lightrail is for lower density, and much more frequent stops. Lightrail is generally used to describe what we used to think of as an interurban. It can fit into the current infrastructure, does not require expensive tunnel construction, but runs at lower speeds because it has to share space with other vehicles. A light rail line is done where you need something a little faster and a little larger than a bus.
Busses, likewise, make tons of sense for much lower density routes, or routes where the density of space usage is too high for any kind of even mildly separated right of way to rob space, but not high enough, or too geologically unstable, to handle a subway.
Whether it makes sense to spend money to make them interconnect depends on usage, traffic flow, and all kinds of other things. I am not a Baltimore resident, and haven't even made a cursory examination of its traffic patterns, so I won't even try to form an opinion of how well or how badly the system works for its normal users.
While connections between modes make sense, if it costs, lets say, $350 million to create that connection, and estimates suggest that perhaps 30 people a day will make that connection, the connection is pointless. Especially if the advantage of connection for those 30 people is not having to walk 100 yards out of doors.
