I think the tradition of the race is dependent on the plodders who trail behind, and I would not like to see Boston lose the tradition by cutting any of those who would try to take on the challenge presented by the race. A marathon is an individual's battle with himself. Every runner should have a chance to wage this battle and have the company of others of similar ability. By allowing all to compete, this is insured. Most joggers have only run 7 or 8 mile training runs, and by running a marathon they are a health hazard to themselves.
Competition defeats the purpose of jogging.
Moreover, joggers clutter up the field and make the race into a Halloween party, a farce. For the serious runner, the mass of joggers at the start is trouble. Along the route they are a hazard to themselves and to traffic which can't be kept off the course all day. They are an unnecessary nuisance. Everyone who competes has set some sort of goal or objective, regardless of ability.