I’ve been playing 2 months and still have several things that are a mystery to me.
What good are the gold cards other than they look neat? If I make a whole deck of gold cards do I get something? What is their purpose?
What is the point of some cards having a blank box? (i.e. no battle cry or anything else) Why would you choose these?
The only benefit you get from an all golden deck is that The Coin will be golden as well.
And you are right that the golden cards offer zero gameplay benefit over normal cards; it’s just visuals.
Those are cards that have no effect other than being a minion with (generally good) stats.
The reason you pick these is that these just offer stats on the board. However, in modern constructed, due to how much better cards have gotten, they rarely see play.
In the starting days of Hearthstone, a card like Chillwind Yeti offered 4/5 stats for 4 mana and that was a good stat-line even without additional effect. Now there are simply better cards for the same mana cost.
In an Arena draft, depending on the alternatives offered, a “blank box” card can be the best option.
Note that just like they cost more dust to craft, golden cards produce more dust when disenchanted, so there is that. Generally speaking, a golden card when disenchanted will produce enough dust to craft a regular card of the same rarity. So if you don’t care about the pretty sparklies, pulling a golden card gives you a leg up on assembling the deck you want. Still, a bit of care is called for; if it turns out you need that particular card and you don’t have a play set of regular ones (doing a collection search for “extra” will help flush out those golds you absolutely don’t need), dusting a gold one means you’ve just traded it for a regular version to no purpose.
I thought the gold cards disenchanted for more dust (but did not grant any combat benefits in-game).