There are some advantages.

• Simpler data setup (one product and then multiple variants)
• Ordering can be easier with variants (Odoo can display the list of variants in a grid)
• BoMs could be easier (one BoM with a list of common components and then any that only apply to some variants).  You can choose whether to have BoMs for products or variants.
• You can create variants on demand (e.g. door is available in 20 colours, but you only create each one when you first sell it).

But it could be easier without variants!  

• Adding attributes to a product is allowed, but can cause problems
• Not all data can be setup for variants

I wrote about this here