Interestingly the quasi-denomination called The Church of Christ which came out of the Restorationist movement in the 19th century has what I would call a deliberately undeveloped theology. They deny Justification by Faith Alone because the Scripture doesn't explicitly teach the alone part. It also says we are Justified by Grace. It also says we are Justified by the Blood. They don't try to systematize, harmonize, or reconcile these articles. They just leave them be, because that's what the Scripture says.
Juvenile perhaps, but interesting. There is a danger in an undeveloped theology but there is also a danger in an overdeveloped theology. When your grid has blank intersects and you are prompted to push and ask questions like- Is the order of the decrees Supra- or Infra- lapsarian…or concerning the origin of the soul…is the Creationist or Traduceanist position correct? At this point, the Bible is not driving your theology…..your system is……more particularly you Epistemology is. More on that later….a huge issue for the contemporary church.
The Church of Christ also teaches Baptismal Regeneration because there are texts to support it. They don't explain it away because of earlier established systematic presuppositions? Are they right? Yes and no.
With the dissenters you seem to find this more undeveloped type of thinking. They wanted to obey the Scriptures. Did they view it as a Redemptive-History or a Legal Text? Probably more like a legal text, but there was some consciousness of Redemptive-History because they saw a significant difference between the Old and New Covenants. This helped define their main argument with Rome.
They didn't teach Sola Fide, they believed in trying to literally follow the Sermon on the Mount and they seemed to adhere largely to other medieval notions like Baptismal Regeneration. Now was it Sacerdotal Roman Baptismal Regeneration or was it a conscious Covenantal Category…understanding that it must be undergirded with a true evangelical faith? Anachronism many would cry at this point! Perhaps. BUT, they seemed to view themselves as a sort ecclesiola in ecclesia…a true remnant within a larger frame. This shows two-tiered thinking….maybe they applied that to their understanding of the Sacraments….but probably not.
The Scriptures do teach Baptismal Regeneration…but it is how we understand it that is critical. Is it the Word plus a sign……..everything and nothing? Or is it salvific ex opere operato in and of itself…the actual water?