I think the Starter Pack in its current form is a mistake cause it will hugely devalue the average regular pack (which consists of 4 commons and 1 rare).

Booster packs have chances to receive Epic, Legendary, and Gold Foil cards which Starter packs do not, and the expected value (in DEC terms) of both types of packs is very similar. That was done on purpose so that the new packs would not devalue the standard Booster packs.

The average cost per card is also very similar in the Starter and Booster packs, so there is no reason why they should "flood the market", and additionally all the players who purchase Legendary and Alchemist packs will receive far less Common and Rare cards per dollar spent, which should work to counteract any increase in circulation of those cards from the Starter packs, and could potentially even cause those cards to be less available than normal.