My reason to include off street parking is due to the current lack of on street parking for retail and professional visits downtown.  Eugene allowed development without off street parking for businesses years ago when the population was much smaller than it currently is, I don't think the City planners at the time envisioned the current growth of Eugene. 

The mention of the parking garages by an earlier respondent is noted as a reasonable alternative, but due to a frightening experience in the garage at 10th and Oak Street many years ago, I never use the downtown parking garages when I'm by myself.  Also, I know several people who won't use them because of the current population of miscreants that have taken up residency downtown. 

Another factor to consider about parking a block or two away from the apartment is the unpredictability of Oregon weather, tenants won't  want to make multiple trips carting items from their car in the rain,  they'll park on the street by the building.