PHJim, was that a question? If so:

The tuning in fourths and smaller intervals (normal guitars, ukes) produces better voicings of strummed chords, compared to a tuning fifths which allows for a larger range, as often welcome for melodies. Moreover, proper mandolins are designed for typical mandolin techniques at considerable expenses, which would be wasted on strumming.

Tenor guitars are ... um, let Will Fly explain.