I do think it's kind of odd that almost all the discussion in this thread has centered around enchantment-style triggers, e.g. "whenever a creature...".
On the creature itself I like the Hearthstone style shortening.
"Whenever CARDNAME enters the battlefield..."
versus
"Summon - "
Especially when CARDNAME is long, that first phrase can be like 8 words or what is basically filler text.
I'm definitely of the opinion that MTG cards try to do too much on average. Here's a card.
Would you believe that this is the
wordiest card in all of Hearthstone? Granted, there's the whole digital versus physical issue, but after spending some time with Slay the Spire and Hearthstone* (two games with no shortage of strategic depth), the textiness of Magic cards is pretty off-putting.
I think part of it comes down to the mana / card draw system. In MTG, because you're playing lands and spells (but only drawing one card a turn), your hand size shrinks quickly unless you are actively drawing additional cards. In Hearthstone you get card draw / generation / discovery stapled onto pretty much everything, so often your hand balloons up to 10 cards and then stays that way until your deck empties. In Spire you see 5 fresh cards every turn. The rate at which you see 30 cards is so much faster in Hearthstone / Spire than in MTG. So in a way I get the complexity differences (with fewer cards seen, you might want your cards to do more per card), but I do think MTG's design has historically been very undisciplined.
There's a lot of complexity that doesn't translate to depth.
I had a discussion / interview with a designer, and during it we tried designing some custom Hearthstone cards to fit a theme. I had some ideas, but when I tried to template them they were just so much wordier than I expected. They were MTG style designs, but they simply didn't fit on four short-lines of text real estate. Ultimately I realized that the card I was trying to make should just be three different, simpler cards (and leave it to the player to mix and match as they see fit).
* some Hearthstone cards you need a whole wiki to fully grok (looking at you Zephrys), so what's on the tin isn't really all there is, but on the whole I prefer the elegant card approach.