The Diaconate did not feature particularly largely in the Decrees of Vatican II. A quick trawl has revealed to me only Lumen Gentium 29 etc.; 41; Ad Gentes 16; Sacrosanctum Concilium 35. SC says that deacons can preside at Services of the Word, to which I can think of no objection. AG advises that those unordained laymen who are de facto fulfilling diaconal roles shoud be ordained deacons so that they can be "altari arctius coniungi", which I think implies rather nicely the essentially cultic nature of the diaconate. LG 41 gives no suggestion that deacons are to be philanthropically inclined; there is just the tiniest hint of this in LG 29, where a sensible list of cultic activities is concluded by 'ministries of charity' (likewise, in AG the de facto deacons might have been charitably occupied). I am not concerned to argue that deacons should never have anything to do with any charitable exercises, so I don't strongly object; if it is true that here the idea of 'diaconate as service to the needy' is getting a bit of an objectionable foot in this door, well, I think this is satisfactorily outweighed by the essentially cultic job-description given for the diaconate, and by the repeated references to the performance of diaconal functions "in conjunction with the Bishop and Presbyterate". So, in this particular matter, Vatican II need cause no problems to those of us whose thought has been formed by the Tradition.
Neither does the Catechism of the Catholic Church. Paragraph 1569 very laudably draws upon the Tradition to remind us that the Deacon "speciatim annecti" to the Bishop, which is why only the Bishop (and not also the Presbyterium) lay hands on him. Even more satisfactorily, 1541 alludes to the Aaronic priesthood and the services of the Levites as prefiguring the ordained ministry of the New Testament, and the next two paragraphs appropriately quote the Prayers of Ordination in support of this; including a section (ancient and authentic) from the Prayer for the Diaconate.
I have discovered in these two major documents of the Magisterium of the last six decades no suggestion that the essence of Diaconate is found in service to the needy, or any determination to import S Stephen and the Seven into consideration of the Diaconate. Nothing in them contradicts the teaching of the old Roman Prayers of Ordination.
So, despite having no mandate from the Council to change the Church's teaching on Holy Order as expressed in her lex orandi, the activities of the post-Conciliar liturgical 'reformers' offered us, as they so often did, an unedifying example of illiterate mischief. As so often, they gave us a sound lesson on how to eliminate babies without losing a single drop of bathwater. They corrupted the Roman Ordination Rites, and did so contrary to both the oldest Roman Tradition and the consensus of 'modern non-Catholic New Testament Scholarship'. That is quite some achievement! To be wrong in the court of each of those two very different judges!