It wouldn't; it is one example of many circumstances that tend to arise in a long-term relationship that make it difficult to unwind regardless of legal status. The legal protections inherent in marriage can actually be desirable when unwinding a relationship.

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I suppose it is favorable if you have a cohabitating partner who is a homemaker since you can pretty much leave them high and dry with only conscience to stop you.

That's probably a better way to frame it than my overly-snarky quip.

Marriage doesn't automatically include children either.

As for the easy escape hatch...a marriage is as simple to dissolve as the parties make it. An acrimonious common-law relationship (if your jurisdiction has such things) is easily as complicated to end as a traditional marriage.