Not necessarily an issue. Ottawa's low floor system has island platforms downtown and has erected barriers between the two tracks. Many platforms in London are island (especially the elevated stations) and there's little problem with people hopping onto the tracks. Although, to be fair London has electrified third rails whereas Ottawa and Edmonton have overhead power supply.
Then you're going to have to flip all the side platform stations to centre island. Grey Nuns, Millbourne/Woodvale, etc. all have platforms directly opposite one another. Avonmore and some of the planned stations in the Brewery District have staggered platforms due to street width, but at the others, running across from one platform to another is theoretically an issue.
Theoretically, at-grade will have people running over tracks no matter what.
I agree, and I would point out that the benefit vis a vis your car/SUV/truck swings more in LRT's favour if the time savings on LRT are more pronounced. We probably won't have that benefit here with the travel times they are forecasting. I still think the LRT will be an attractive option, but I do not think that its relative slowness is what makes it attractive.
I still suspect that we will end up adding crossing gates to certain intersections on the Valley Line. The ION LRT is similar to the Valley Line in many ways and is street-running in some areas, but it still has crossing gates in places, particularly when it crosses major roads. The LINK LRT in Seattle is an interesting hybrid with segments that run down the median, some elevated stations, some underground stations and a downtown tunnel shared with buses. But it also has crossing gates in some spots.
I've lived here too long to trust that "everything's going to be alright." As I've said before, we were told by city "experts" that congestion and cross traffic wouldn't be a major problem at University Ave/114 St, at the Metro Line grade crossings and on the Capital Line at Southgate. In each case, the city was proven wrong: it was and is a huge problem. The same brilliant minds have decided that we don't need crossing gates on the Valley Line because urban style LRT is oh-so-trendy.
The accidents in the street-running portions can be prevented by placing bollards along the edges of the line, as we would with our standard high-floor LRT. The collisions caused by drivers turning in front of the train--and by drivers running lights--can largely be prevented at major intersections with crossing gates. But I'm glad you linked that video, it does help make my point about the flaws of urban-style LRT with so-called "minimal impact on the streetscape."