For me, I couldn't care less about the mechanical implications of the combo. The very first thing I'd be asking and witnessing as the player created and played the character would be who this character is, why did it start as a monk, and where/when/why did it become a druid?
So much yes, from my particular gaming style.
There are DMs whose style is adversarial: they throw the biggest baddest monsters and the cleverest traps at the PCs (with no regard for pesky questions such as "what sane NPC would have spent the resources required to build this trap?"), they try to kill off PCs, and the players whose PCs survive are the winners. The current DMG doesn't particularly recommend this style, but it's how some tables roll.
There are players and DMs who play D&D as a rules war; the players seek the most advantageous builds, the DM argues with rulesbook in hand, the player who can most separate RAW from RAI wins, and their PC dominates the party. Not what I enjoy, but de gustibus nil est disputandem.
There are players and DMs who use a TRPG to end up with an awesome story; a story which, as a movie or comic book or whatever, would be one of their favorites... though for some of us the ideal fantasy story is Princess Bride, and for others that means LotR. That's my preferred style of play. This style doesn't have much room for co-existence with either of the previously-summarized playstyles.
I'm playing a half-elf who discovered the magic of music, started as bard, levelled to Bard 3. Then, as a PC in "Tales Trees Tell", she met an NPC druid, travelled into the Feywild, talked with NPCs in Sylvan, and decided to explore the Wood Elf side of her ancestry by learning druid magic. Was she more powerful as a Bard 3 Druid 1, than she would have been as a Bard 4? Maybe; Bard 4 gets an ASI/feat, while Druid 1 gets a few cantrips and another spell list, plus a language (Druidic). Maybe. But I had *more fun* playing *that character* as Bard3/Druid1, than I would have had playing her as Bard4. When we played "Shadow over the Moonsea", she used Speak with Animals to talk a dire wolf out of a fight and interview it for clues, and later on, to redirect a shark towards the pirates ("eat THEM, they're delicious!") rather than her allies. What feat could possibly give me - *and the other players* - so much entertainment at the table?
Okay. That's my core perspective. As a DM: when a PC has adventured enough and is ready for further training, I want the player to decide *what their character would do from an internally-consistent set of character motives*. If that's a PC monk saying "I wanna get to the roots of martial arts, practice Bear Style as a bear and Crane Style as a crane", then they can go find an NPC druid and persuade that NPC to initiate them into the druidic mysteries. Meanwhile, if a PC druid says "hmm, I'm strong and fast as a bear or a wolf, but my fighting is sloppy, who could teach me to fight better?", then that PC druid can go stand outside a monastery in the rain until the NPC monks accept a new trainee. Or the PC can go find a barbarian tribe, since barbarians fight unarmored and have totem animals, and that eventually leads to Enraged Wild Shape. Or one then the other. This involves falling behind on the spell slot chart, and the benefits of cross-class Wild Shape will never match the firepower of Call Lightning. But the PC is *following their dreams*.
***
Addressing a minor questions which arose incidentally: the hen/turtle/dove/partridge/pear grows in pear trees, in the former orchard around the ruined tower of the mad wizard who created owlbears. As for "Christmas trees", none of the campaign settings published by WotC describe Christianity as an in-game religion (and that's a wise decision for an American publisher). You could try grafting the pear stem of the HTDPP onto a branch of a fir tree...
(...wait for it...)
...if your DM allows "firries".