I'm extremely hard-pressed to think of any situation where I'd rather draw two cards than win the game.
You might be in the minority of Vintage players.
Restricting Mishra's Workshop puts the current artifact decks in the realm of Goblins and Enchantress. The only reason one would argue for this restriction is if they want to nuke the archetype from orbit.
If the decks are making up this portion of the metagame, where are the delvers? Or ancient grudges? Where the hell did Dack Fayden go? Letting shops win events because it is disrespected is not a problem inherent to the format, but the players.
Chalice isn't around anymore to derp you out of your moxen. Lodestone Golem has retired from the days of bashing your face in before you can play some land. Want to beat shops? Add more mana to your deck and start cutting some of the dead maindeck cards. Oh, and this same thing will help your Eldrazi matchup, too.
You can't be first in the blue mage arms race and expect to have a good matchup against decks built to punish your greed.
Workshop win percentage against the field? ~60%
Mentor had essentially the same win percentage. Paradox had an even greater one.
Workshop percentage in top 8: 50%
Workshop percentage in top 4: 75%
Oh that is troubling. I wonder what won it? Hey look, a deck running 27 mana sources and ZERO dead maindeck cards against Shops.
@bobbyvictory Thorn of Amethyst and Monastery Mentor were restricted less than two months ago. Blue decks haven't even had a chance to get their feet under them yet, and, as @JACO has pointed out, were grossly misbuilt for this Champs. Vintage is a format about slow changes and I know there is a large segment of the population that is sick of huge changes looming.
Not every metagame problem should be solved with a restriction. Perhaps people simply need more time to figure out how to beat the robot menace, like has happened for years.
Shops are just much more powerful, flexible and adaptable than they have ever been.
This is objectively false. Modern Shop decks are no where near the power level of the 4x LSG, 4x Chalice decks. I can respect an argument that the archetype could be too strong right now but let's not get carried away with hyperbole: we are no longer in the era of "oops I'm dead before I can play spells".
Shops simply has the best set of cards among the different archetypes trying to play standard Magic.
Have ... have you seen the restricted list? The best cards on there are blue and they're in all blue decks. Shops having the best unrestricted card is an arguable point. Perhaps even Shops having the best unrestricted cards, multiple, could be argued. There's no reason for hyperbole, though.
I think @Oestrus has an amazing point and I would hate to see it dismissed for silly reasons. Dredge and Shops have both been the traditional Vintage fun police, they both have traditionally been "run enough/draw enough sideboard cards and you win" matchups, and both have been proven to have staying power. Why is there such a disparity in attitude between them?
I wonder how much of the "blowout effect" @POXEVERYTURN mentions factors into this. Do blue players not understand the shops matchup? Are they overestimating their preparedness for it due to winning long, grindy, unfavored matches against mediocre opponents? Or is the deck really the purported steamroller everyone is posting about? I am not sure, but it seemed like most of my blue opponents at champs were woefully unprepared. It went as far as one opponent showing me his sideboarding plan and telling me point blank "I netdecked this list and have no idea how it's supposed to beat you with all of these dead cards".
(b) reduce the inclination for Shops decks to play tax effects
This is not their logic. Their logic is that people will have to stop playing shitty manabases now that they can't justify them with free spells.
Can we please stop spouting this nonsense that the way to beat shops is having more lands in your deck? Its just not true. Its been said on these boards in the past and its been shot down on these boards in the past.
And this is why mana denial decks will keep winning.
I think if you cut 3 workshop and added city of traitors, mana vault, and maybe some metalworker, Shop decks would survive just fine. They'd be taken down a peg, but it's hardly eradicating the deck. If the deck is worthless -3 workshops, your basically saying a workshop deck can't win unless it has workshop in its opener. That's hardly the case. Workshop in the opener (plus moxen) make it degenerate, but it is not a useless nerfball without workshop by far.
The point you're missing here is that the key strength of the Mishra's Workshop deck is consistency. Ancient Tomb smooths things over decently when you don't hit your namesake card and nothing else even comes close. Shop as a 1-of turns the deck into inconsistent garbage.