99.9% of the time, paying with bitcoin goes through a payment processor such as bitpay, bitpay instantly sells your bitcoins for FIAT hence putting sell pressure on the market. So basically if people take your advice right now and start buying products with bitcoins, the price will fall.
If nobody uses Bitcoins for transactions, interest in Bitcoin will decline. Without transactions, Bitcoin is a penny stock with no assets behind it.
newegg do not sell groceries or consumables that need purchasing every week. they know that their business model is such that peopl will only buy a TV/computer once every 4 years.
their business model is not based on repeat business everyweek.
newegg, overstock dont really care about repeat business of large goods and all negative points raised about bitcoins usability have nothing to do with raising the market price nor raising merchants desires to continue accepting bitcoin.
for instance overstock CEO see's the real benefits of bitcoin and is not worried about any negative crap said in this topic, he see's the bigger long term picture