Reasons for having automaticity with single-digit times tables (from the perspective of a community college lecturer with many remedial courses):
- Long multiplication algorithm
- Long division algorithm, and thus:
- Convert fractions to decimals
- Understand why rational numbers have repeating decimal expansions
- Understand the proof why $\sqrt{2}$ is irrational
- Factor integers, and thus:
- Understand the Fundamental Theorem of Arithmetic
- Reduce fractions by finding the LCD, and thus:
- Add, subtract, multiply, divide, and compare fractions
- Factor polynomials, and thus:
- Reduce rational expressions
- Solve higher-degree equations
- Understand the Fundamental Theorem of Algebra
- Estimations to double-check technology output
Perhaps on a deeper level I'd say that the base-10 place value writing system was architected specifically to easily support these operations, assuming that single-digit elementary operations were memorized (like phonemes) -- so if someone hasn't done that, they're really not using the language correctly.
Students should certainly know how to multiply any arbitrary number by 10. For products of two numbers above 10, I would agree that it's not really critical -- although the 11-table is trivial and knowing the 12-table may be handy when dealing with clocks, inches, and units in dozens (and $12^2$, one gross, does pop up a lot).