Creative deckbuilders will find replacements for those cards and still have fun, or they may even - in a casual setting - ignore the restricted list. (As an aside, this is another barrier which some players impose on themselves which is unnecessary in a casual setting. "If I just had access to this card for my deck," they say, "it would be so much more fun." Does your play group care or even have knowledge of the restricted/banned list? Then play it. Have fun.) This is what the RL is for, to force creativity and hard choices at the expense of the easy choices in a competitive setting, and thereby to keep the game fresh.
This is a bit of an alien view to me. The Restricted list is part of the rules of the game, so in my mind that's kind of like saying "Does your group even know the rules exist?" I can imagine that people exist who play casually and don't look at online resources, I've seen them on BGG for instance, or brand new players who hadn't found it yet, but in general it feels weird to me to consider that people play with half the rules and ignore the other half. But then again, I've never been one for house rules in any form.
That said, we did have a discussion on whether we should still use the Restricted list when playing Highlander format. I hadn't thought of it but Lee brought it up. At the time we decided to enforce it that night because I had built my decks to be compliant but we will talk about it again sometime for future Highlander events.