Not really. I have extensive reasons behind what I suggest. A strategy I use to swiftly prop-up or knock-down a concept is to peg it out near the edge of the envelope. And avoid investing time in precision costings and so on, until after I can sound out if it is reasonable. To give some insight, if we ask ourselves "How might we cause more interactions across things Wizards can do" and consider landmark games such as Cosmic Encounter which basically nailed the answer: we look for combinatorial strategies. Concentration blocks combinatorial strategies (by one character, in regard to their Concentration spells). Many contemporary games benefit hugely from combinatorial mechanics: it's one of the most important discoveries in gaming of the last century. Wizards play out like a grab-bag of powerful, but individual effects. The question isn't one of power, it's of whether more intrigue and diversity can be achieved?
It's true I focus on crunch. That's what interests me. For me, the play comes more out of the crunch than the fluff. Or maybe it is better to say that the fluff is spun out of the crunch? Hence if I want to see diversity in Wizard play, I don't want a novel about their funny frolics and frivolous frocks.
In closing, in this thread it was clear from the first few posts that double concentration is a bad concept - or at least not a good concept in terms of my rough goals - so I responded very promptly acknowledging that. (By the end of page 1, I'd done so!) In other cases, it's not so clear, or I don't yet to my taste see any convincing arguments. Yet I'm grateful and highly value what other posters contribute. It helps illuminate all kinds of new things, new aspects of the game, and factors bearing on a concept that I might very well (and often have!) overlooked.
(NB: I have no "malaise" with Warlocks. I like Warlocks. Very concretely, I want to broaden their viable strategies, which right now are demonstrably over-shadowed by Agonizing EB.)
Uff, that was a hard read. But I got your gist.
If it's creative
spell combos that you're looking to include, there are certainly ways you can do that (e.g. casting any fire spell onto a
grease spell) without needing to undermine the Concentration mechanic to do it. I'm not saying Concentration is perfect (in fact, I think the ways it can be disrupted need reexamination). However, it's core mechanic works well in fulfilling four functions:
1. Preventing "Broken" Spellcasting. Concentration prevents a host of undesirable situations that were present in past editions.
One example of an undesirable situation would be a spellcaster creating a
wall of force or
Otiluke's resilient sphere around himself when surrounded then dropping a
cloudkill. While such a scenario might make the spellcaster drool, it really isn't fun for anyone else at the table. Other PCs are either seeking shelter in the force field or finding ways to survive within the poison gas. There's really a limited set of options to deal with this scenario, mostly involving specific spells like
gust of wind,
dispel magic, and
disintegrate. And a villain using this strategy against the PCs would most certainly be a drag for the players, especially a group that didn't have the right spells to break this "turtling" combination.
Another example would be casting
banishment or
maze on a monster and then
delayed blast fireball or
glyph of warding or some other "trap" spell in the space they will eventually return to.
Another example would be
hold person and any ongoing damage area of effect spell. And so on.
2. Unified Mechanic for Past Edition Language. Many folks don't realize this, but 3e and especially AD&D were rife with language in spell descriptions like "by concentrating on this spell" or "with continued concentration", etc. Concentration reinforces what was restricted to narrative description and often disregarded in past editions.
3. Limits the Spellcaster's Turn Length. Everyone who has played D&D across a couple editions has experienced a spellcaster's turn take agonizingly long as they manage multiple ongoing spells. Concentration (and the cantrip/bonus action spell restriction) helps reduce that effect greatly, making a spellcaster player's turn not take much longer than any other player's.
4. Limits Swiss-Army-Knife-Wizard Overshadowing Other PCs. It's easy to imagine a mage casting
expeditious retreat (Dash as a bonus action) on himself *and*
fog cloud around the trolls, and all of a sudden then the spellcaster is out-roguing the rogue while *simultaneously* performing his function as a mage.
While D&D historically lets mages momentarily step on the toes of other classes (e.g.
arcane lock,
knock), at least 5e provides some limits on that with Concentration.