There's nothing unscriptural about vestments. God commanded that they be used in the Old Testament. Look at Exodus 28:2:
For your brother Aaron you will make sacred vestments to give dignity and magnificence. You will instruct all the skilled men, whom I have endowed with skill, to make Aaron's vestments for his consecration to my priesthood. These are the vestments which they must make: a pectoral, an ephod, a robe, an embroidered tunic, a turban, and a belt. They must make sacred vestments for your brother Aaron and his sons, for them to be priests in my service. They will use gold and violet material, red-purple and crimson, and finely woven linen.
The rest of the chapter gives details on each garment.
Nothing in the New Testament requires abolition of priestly vestments. Our Lord attacked the Jewish leaders for a number of sins, but he never condemned their priestly garb. It's true the early Church didn't use the Old Testament vestments, but this is because Christians didn't want to identify their leaders with the Jewish priesthood.
Part of the problem for Fundamentalists is that vestments set priests apart from the laity. Fundamentalists object to a ministerial priesthood in the Church. They see vestments as a way of expressing a distinction between clergy and laity.
On this they're right, but there's nothing wrong with such hierarchical distinctions. The New Testament is full of them (Acts 20:28; Eph 2:20, 4:11; Phil 1:1; 1 Tm 3:1-13; Ti 1:5).
Within Fundamentalism there's also an unhealthy opposition set up between the spiritual and the material realms. There is an anti-incarnational attitude which views the use of anything material as superstitious. The distaste for vestments is but one example of this.
Fundamentalists who say Catholic priests adopted distinctive dress in the fifth century to put themselves above the laity have got it backwards. Actually, it was the laity who changed their attire, not to distinguish themselves from priests, but to keep up with fashions.
Catholic priests simply retained their manner of liturgical dress. Priestly vestments are no more than stylized secular Roman garments which have accrued symbolic, liturgical significance over the centuries.