Business expenses are deductible whether incorporated or not. The issue is the ability to save hopefully for an adequate retirement. The maximum RRSP contributions will not provide for a retirement equivalent to a retired teacher or firefighter even for someone earning over $200, 000 unless they save additional funds in a non registered account.

So a doctor who starts earning an income at 30, pays off student debt by 35, really only starts saving additional retirement funds after 35 if they live below their means. 

If they get sick they have zero income for 3 months until their long term disability insurance kicks in. This is self funded and costs 5-10 grand a year, and is not tax deductible.
Short term disability is too expensive so most professionals or business owners don't bother. 

The income splitting provisions are reasonable for spouses who in most cases own half the corporations assets (in the event of a divorce) 

Trudeau is out to lunch on these tax measures.