Recently the Diocese of Worcester announced that it was suspending its diaconate formation program pending a thorough review of the pastoral needs of the diocese. You can read about it here. The basic question seems to be: "Do we have enough deacons?"
I simply would like to make two points:
1) No one should ever be ordained to any order (bishop, deacon, presbyter) if there is no pastoral need for that ministry. The ordained ministries do not exist for the good of the ordained themselves, but for the common good and building up of the whole People of God (see, for example, Lumen gentium 18). We don't often think of this important dimension; it is far more common to speak of the vocation a particular person receives and then responds to. When approached in this way, a vocation can be (mistakenly) as a personal thing: "I have received a vocation from God to be [bishop, presbyter, deacon]." However, that is only half the story: an ecclesial vocation is, in fact, just that -- a vocation exercised with and for the Church. Lumen gentium 29 further states: "It pertains to the competent territorial bodies of bishops, of one kind or another, with the approval of the Supreme Pontiff, to decide whether and where it is opportune for such deacons to be established for the care of souls." Therefore, to review the pastoral needs of a diocese in terms of the ordained ministers needed is certainly appropriate.
2) However, here's the rub. The question becomes: How do we determine the needs of the diocesan Church? It is in response to this question that I think we sometimes jump to wrong conclusions. There is too often a tendency to filter this question through pastors and parishes: "What do our parishes need?" "How will the deacon fit into these needs?" But the church is not confined to parishes, nor is the church's service exercised solely through parishes. Certainly it is important to know about specific parochial needs; but we must ensure that someone is assessing the needs of the broader church and community, and this is precisely a principal diaconal venue of service.
The problem really only arises when deacons are understood primarily as PARISH ministers, not if they are understood as ministering in venues that transcend the parish.
Further the "funding" of the diaconate should never come solely from parish resources. Whoever "pays" for something feels like they "own" something. If the deacon is truly a diocesan minister, then the diocese needs to find extra-parochial sources for funding.
In conclusion, I would suggest that it is perfectly reasonable to assess the pastoral needs of the diocesan church for ordained ministry; however, in the assessment of those needs vis-a-vis the diaconate, it should be ensured the widest possible lens be used, and that more than parish-centered needs be worked into the equation.