Why Not Keep Talking about Hercules and the Merchant of Venice?

In Act III, Scene II, another suitor-scene in front of the caskets (as was the previous scene recently discussed on the Campus), Hercules comes up twice. The first is in a speech of Portia:

...Now he goes
With no less presence, but with much more love
Than young Alcides, when he did redeem
The virgin tribute, paid by howling Troy
To the sea-monster: I stand for sacrifice,
The rest aloof are the Dardanian wives,
With bleared visages come forth to view
The issue of th' exploit: go Hercules!
Live thou, I live--with much much more dismay,
I view the fight, than thou that mak'st the fray.

(53-62)

Shortly thereafter, as Bassanio is deliberating his choice and commenting on the deceptive attraction of outward ornament, he states:

How many cowards whose hearts are all as false
As stairs of sand, wear yet upon their chings
The beards of Hercules and frowning Mars,
Who inward search'd, have livers white as milk?--
And these assume but valour's excrement
To render them redoubted.

(83-8)