Whether you like the bumpouts are not, it is simply not true that the bumpouts intrude into the main traffic lane, and I wish people would stop saying that the street has been "narrowed," as if Roncesvalles didn't function as a two-lane street before, with one lane in each direction. The bumpouts widen into the parking lane, not the traffic lane, and they take up space once used by parked cars, not moving cars. I can't see why the Roncesvalles bumpouts should be any more problematic for drivers than the parking bays that are used everywhere (or than parking lanes in general, for that matter).
The real problem currently seems to be that the street is in a state of mid-completion, and so people are mistaking the unfinished and unmarked bike lane that runs alongside the bumpouts for a parking lane. People park in what is in fact a traffic lane, block the streetcar and thus the whole street. Why the city has not placed some pylons or barrels in these locations is beyond me.
People should be more concerned about whether drivers will still think they can park in these locations after the platforms are completed, and the lanes are properly marked and signed. If people still intuitively feel these are parking areas (regardless of signage), then this is a serious problem. I guess we'll find out when everything is finished. But in the meantime, the city should make it clearer where people can and cannot park. (I mean really -- all it would take is a few orange barrels with "no parking" written on them.)