@Grish
Easy there fella... I'd just as soon chew out a Chaos Dwarf player fielding 2 shakers and 6 bolt throwers. That's 'ard boyz mantra! Most folks on CDO would probably agree too. As is 11 PD+ in my book. Outside of 'ard boyz, where anything goes, I would never field a 2nd shaker until about 4,000 points. Nor am I keen on Bolt Thrower spam. I tend to have a single shaker and a single death rocket and rarely a single bolt thrower for my shooting for my Chaos Dwarfs. I do quite well with them too!
The thing is, I'd argue magic can be A LOT more powerful than warmachines. Even if they don't misfire, or misjudge range... those can still drift... roll poorly on partials, etc. Plus, I'd argue there are far more ways to deal with warmachines than magic (especially if they don't have a hill to park on). Whereas casters can sometimes be effective in combat (Vampires, Chaos, Daemons, Plague Priests) too. Furthermore there are FAR more magic items to enhance the ability to get magic to work and/or its effectiveness. Only the Dwarfs, via runes, have anything to help shooting... and the most commonly chosen either make them flaming attacks or make them safer to use!
The problem with Gunlines is, usually they're not effective enough to prevent the enemy from getting to them. Once they do, the gunline is dead... dead... dead. Even standard troops can cut warmachine crews/missile units with relative ease. The difference is magic heavy armies don't automatically sacrifice everything else to get good in magic. So being high magic doesn't translate to a weak "rest of the army". Typically gunlines sacrifice most/all their specials and/or rares.
As MS said, the strength/weakness of my warmachines does not automatically ruin/enhance yours. Can an Empire player go counter battery fire? Sure. Also spreading his cannons apart could reduce my chances of silencing them in the case of a shaker firing. If he has zero warmachines are mine going to destroy him? No, as there are several of ways to counter it in and out of the shooting phase (mobile units, other shooting, magic, planned movement, using terrain to limit targets, meat shields, getting into combat sooner, etc). Plus it doesn't make it easier for me to be accurate/get partials/wound either. Where as magic defense can really only be done in one phase of the game, it emphasizes that phase of the game way too much.
Especially when some of the best magic in the game is supportive and not offensive magic resistance won't help there... or for offensive spells he might simply shift targets... so the MR only helped once maybe twice. Positioning doesn't always help as not all magic needs line of sight.
Look at it this way. If I buy scrolls, items that generate extra dispell dice, etc... but I go against a low magic player (especially Dwarfs) all that is wasted. It's rare, but it happens. Where my counters for warmachines might find other uses. These uses might be less effective, but they still have value.
Kind of a big point
The other defenses you mention tend to be multi-purpose. What I can use for monster defense, I might be able to warmachine hunt with or frenzy bait with. What I can use to redirect/channel some units I might be able to use as a meatshield. So on and so forth. Whereas magic defense is pretty much single purpose.
If there were easier/multipurpose ways to generate magic defense.. as you said... I agree it'd be less annoying. However I don't want to enter a new edition where dispelling is harder without those "more/easier" methods in effect. Having a "range"/"cover" penalty for some spells might be nice. Making the magic phase a little more interesting than "simply roll to cast" and "roll to dispell" would do more to make interesting, than simply fielding more magic.
Also VERY important
Please take what I have said with respect. I'm a little out of it due to meds I'm on this week (I look forward to having the operation performed), so I hope I don't come across as crass or rude... so I hope I worded my thoughts respectfully and with attention to why I do disagree so strongly.
Though I was a little annoyed by the "two shakers" comment, I will admit... but I do see how 2 shakers could quickly be annoying... thus what I said above.
@ Kaptain Von: While I tend to prefer Nurgle, I completely sympathize with you. Khorne fans should be allowed to field pure Khorne and still do well! I'm all for mono-god Chaos. I do wish they had a nice middle ground between the old Mark of Khorne and the new one. Characters, and perhaps Chosen, should still generate dispell dice... and/or have it as a cheap (and reusable) gift available to Khorne. T
You kinda hit on why the increasing need for magic defense worries me. It destroys the chances for certain themes to work. Khorne armies, "wizards are bad"/witch hunter Empire armies, and others I'm sure.
Magic should certainly be a component, it is a fantasy genre game. There is a difference to being a flavor in the game, and overpowering it! If this was a burrito we've gone from zesty to volcano. For those who love magic heavy, like those who like spice, this is ok. Making magic defense harder (though I can understand certain thematic qualities) would push it to "This burrito is a nuclear reactor in disguise". I honestly think it could kill the game where things currently stand... and burritos that can power my hometown scare me.